Optical System for Reference Switching

ABSTRACT

Systems and methods for determining one or more properties of a sample are disclosed. The systems and methods disclosed can be capable of measuring along multiple locations and can reimage and resolve multiple optical paths within the sample. The system can be configured with one-layer or two-layers of optics suitable for a compact system. The optics can be simplified to reduce the number and complexity of the coated optical surfaces, et al. on effects, manufacturing tolerance stack-up problems, and interference-based spectroscopic errors. The size, number, and placement of the optics can enable multiple simultaneous or non-simultaneous measurements at various locations across and within the sample. Moreover, the systems can be configured with an optical spacer window located between the sample and the optics, and methods to account for changes in optical paths due to inclusion of the optical spacer window are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 62/325,908, filed Apr. 21, 2016, which is hereby incorporatedby reference in its entirety.

FIELD

This relates generally to a reference switch architecture capable ofdetecting one or more substances in a sample, and more particularly,capable of reimaging one or more optical paths in the sample.

BACKGROUND

Absorption spectroscopy is an analytical technique that can be used todetermine one or more properties of a sample. Conventional systems andmethods for absorption spectroscopy can include emitting light into thesample. As light transmits through the sample, a portion of the lightenergy can be absorbed at one or more wavelengths. This absorption cancause a change in the properties of light exiting the sample. Theproperties of light exiting the sample can be compared to the propertiesof light exiting a reference, and the one or more properties of thesample can be determined based on this comparison.

The properties of light exiting the sample can be determined usingmeasurements from one or more detector pixels. Measurements alongmultiple locations within the sample may be useful for accuratedetermination of one or more properties in the sample. These multiplelocations can be at different locations in the sample, which can lead tooptical paths with different path lengths, angle of incidence, and exitlocations. However, some conventional systems and methods may not becapable of discerning differences in path lengths, depths ofpenetration, angles of incidence, exit locations, and/or exit anglesfrom measurements along multiple locations within the sample. Thosesystems and methods that can be capable of measurements at multipledepths or multiple locations can require complicated components ordetection schemes to associate optical paths incident on the multiplelocations within the sample. These complicated components or detectionschemes may not only limit the accuracy of reimaging and resolving themultiple optical paths, but can also place limits on the size and/orconfiguration of the optical system. Thus, a compact optical systemcapable of accurately reimaging and resolving multiple optical pathswithin a sample may be desired.

SUMMARY

This relates to systems and methods for measuring one or more propertiesof a sample. The systems can include a light source, optic(s),reference, detector array, and controller (and/or logic). The systemsand methods disclosed can be capable of measuring one or more propertiesat multiple locations within the sample. The systems and methods canreimage and resolve multiple optical paths within the sample, includingselecting a targeted (e.g., pre-determined) measurement path length suchthat the spectroscopic signal quality measured by the detector canaccurately represent one or more properties of the sample. The systemcan be configured with one-layer or two-layers of optics suitable for acompact (e.g., less than 1 cm³ in volume) system. The optics can besimplified to reduce the number and complexity of the coated opticalsurfaces, etalon effects, manufacturing tolerance stack-up problems, andinterference-based spectroscopic errors. The optics can be formed suchthat the number of moving parts can be reduced or moving parts can beavoided, and robustness can be enhanced. Furthermore, the size, number,and placement of the optics can enable multiple simultaneous ornon-simultaneous measurements at various locations across and within asample, which can reduce the effects of any heterogeneity in the sample.Moreover, the systems can be configured with an optical spacer windowlocated between the sample and the optics, and methods to account forchanges in optical paths due to inclusion of the optical spacer windoware disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a block diagram of an exemplary system capable ofmeasuring one or more properties located at multiple locations within asample according to examples of the disclosure.

FIG. 1B illustrates an exemplary process flow for measuring one or moreproperties located at multiple locations within a sample according toexamples of the disclosure.

FIG. 2 illustrates a cross-sectional view of an exemplary systemconfigured to determine one or more properties of a sample according toexamples of the disclosure.

FIG. 3 illustrates a cross-sectional view of an exemplary systemconfigured to determine one or more properties of a sample according toexamples of the disclosure.

FIG. 4A illustrates a cross-sectional view of an exemplary portion of asystem configured for resolving multiple angles of incidence on a samplesurface with two-layers of optics according to examples of thedisclosure.

FIG. 4B illustrates an exemplary junction coupled to light sourcesaccording to examples of the disclosure.

FIG. 4C illustrates an exemplary waveguide coupled to light sourcesaccording to examples of the disclosure.

FIGS. 4D-4H illustrate cross-sectional views of exemplary optics layersincluded in a system configured for resolving multiple optical paths ina sample according to examples of the disclosure.

FIG. 4I illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple angles of incidence on a samplesurface and reducing or eliminating trapped light from light sourcesaccording to examples of the disclosure.

FIG. 5 illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple angles of incidence on a samplesurface with one-layer of optics according to examples of thedisclosure.

FIG. 6 illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple optical path lengths withtwo-layers of optics according to examples of the disclosure.

FIG. 7 illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple optical path lengths withone-layer of optics according to examples of the disclosure.

FIG. 8 illustrates Snell's Law according to examples of the disclosure.

FIGS. 9A-9B illustrate top and perspective views of an exemplary groupincluding an optics unit according to examples of the disclosure.

FIG. 9C illustrates a top view of exemplary multiple groups includingoptics units and detector arrays in a system according to examples ofthe disclosure.

FIG. 10 illustrates an exemplary configuration with light rays having aspatial resolution uncertainty according to examples of the disclosure.

FIG. 11 illustrates an exemplary configuration with light rays having anangular resolution uncertainty according to examples of the disclosure.

FIG. 12 illustrates an exemplary configuration with an input light beamwith a Gaussian angular divergence according to examples of thedisclosure.

FIG. 13A illustrates a cross-sectional view of an exemplary systemincluding an optical spacer window and aperture layer located betweenthe optics unit and the sample according to examples of the disclosure.

FIG. 13B illustrates a cross-sectional view of an exemplary systemincluding an optical spacer window located between the optics unit andthe sample according to examples of the disclosure.

FIG. 14A illustrates a cross-sectional view of an exemplary systemexcluding an optical spacer window and corresponding determination ofthe lateral position of light incident at the exterior interface of thesystem (e.g., interface where the system contacts the sample) accordingto examples of the disclosure.

FIGS. 14B-14C illustrate cross-sectional views of an exemplary systemincluding an optical spacer window and corresponding determination ofthe lateral position of light incident at the exterior interface of thesystem (e.g., interface where the system contacts the sample) accordingto examples of the disclosure.

FIGS. 14D-14E illustrate cross-sectional views of an exemplary systemincluding an optical spacer window according to examples of thedisclosure.

DETAILED DESCRIPTION

In the following description of examples, reference is made to theaccompanying drawings in which it is shown by way of illustrationspecific examples that can be practiced. It is to be understood thatother examples can be used and structural changes can be made withoutdeparting from the scope of the various examples.

Representative applications of methods and apparatus according to thepresent disclosure are described in this section. These examples arebeing provided solely to add context and aid in the understanding of thedescribed examples. It will thus be apparent to one skilled in the artthat the described examples may be practiced without some or all of thespecific details. Other applications are possible, such that thefollowing examples should not be taken as limiting.

Various techniques and process flow steps will be described in detailwith reference to examples as illustrated in the accompanying drawings.In the following description, numerous specific details are set forth inorder to provide a thorough understanding of one or more aspects and/orfeatures described or referenced herein. It will be apparent, however,to one skilled in the art, that one or more aspects and/or featuresdescribed or referenced herein may be practiced without some or all ofthese specific details. In other instances, well-known process stepsand/or structures have not been described in detail in order to notobscure some of the aspects and/or features described or referencedherein.

This disclosure relates to systems and methods for determining one ormore properties of a sample. The systems can include a light source,optics, reference, detector array, and controller (and/or logic). Thesystems and methods disclosed can be capable of measuring along multiplelocations within the sample to determine the one or more properties. Thesystems and methods can reimage and resolve multiple optical pathswithin the sample, including selecting a targeted (e.g., pre-determined)measurement path length such that the spectroscopic signal qualitymeasured by the detector can accurately represent the one or moreproperties of the sample. The system can be configured with one-layer ortwo-layers of optics suitable for a compact (e.g., less than 1 cm³ involume) system. The optics can be simplified to reduce the number andcomplexity of the coated optical surfaces, etalon effects, manufacturingtolerance stack-up problems, and interference-based spectroscopicerrors. The optics can be formed such that the number of moving partscan be reduced or moving parts can be avoided, and robustness can beenhanced. Furthermore, the size, number, and placement of the optics canenable multiple simultaneous or non-simultaneous measurements at variouslocations across and within a sample, which can reduce the effects ofany heterogeneity in the sample. Moreover, the systems can be configuredwith an optical spacer window located between the sample and the optics,and methods to account for changes in optical paths due to inclusion ofthe optical spacer window are disclosed.

Absorption spectroscopy is an analytical technique that can be used todetermine one or more properties of a sample. Light can have an initialintensity or energy when emitted from a light source and incident on thesample. As light is transmitted through the sample, a portion of theenergy can be absorbed at one or more wavelengths. This absorption cancause a change (or loss) in the intensity of light exiting the sample.Light exiting the sample can be due to light that scatters from one ormore locations within the sample, wherein the location can include asubstance of interest. In some examples, the substance of interest canbe present in some or all of the path of light into and/or out of thesample, where the measured absorbance can include absorption at one ormore regions where the light scatters. The amount of light exiting thesample can decrease exponentially as the concentration of the substanceof interest in the sample increases. In some examples, the substance caninclude one or more chemical constituents, and the measurement can beused to determine the concentration of each chemical constituent presentin the sample.

FIG. 1A illustrates a block diagram of an exemplary system and FIG. 1Billustrates an exemplary process flow for measuring one or moresubstances located at multiple locations within the sample according toexamples of the disclosure. System 100 can include interface 180, optics190, light source 102, detector 130, and controller 140. Interface 180can include input regions 182, interface reflected light 184, reference108, and output regions 156. In some examples, input regions 182 and/oroutput regions 156 can include an aperture layer including one or moreopenings configured to limit the location and/or angles of light exitingand/or entering the system. By limiting the location and/or angles oflight exiting and/or entering the system, the light incident on orexiting from sample 120 can also be limited. Optics 190 can include anabsorber or light blocker 192, optics 194 (e.g., a negative micro-lens),and light collection optics 116 (e.g., a positive microlens). Sample 120can be located near, close to, or touching at least a portion of system100. Light source 102 can be coupled to controller 140. Controller 140can send a signal (e.g., current or voltage waveform) to control lightsource 102 to emit light towards the surface of sample 120 (step 153 ofprocess 151). Depending on whether the system is measuring the one ormore properties of the sample or of the reference, light source 102 canemit light towards input regions 182 (step 155 of process 151) orreference 108.

Input regions 182 can be configured to allow light to exit system 100 tobe incident on sample 120. Light can penetrate a certain depth intosample 120 and can reflect and/or scatter back towards system 100 (step157 of process 151). The reflected and/or scattered light can enter backinto system 100 at output regions 156 (step 159 of process 151). Thereflected and/or scattered light that enters back into system 100 can becollected by light collection optics 116, which can redirect, collimate,focus, and/or magnify the reflected and/or scattered light (step 161 ofprocess 151). The reflected and/or scattered light can be directedtowards detector 130. Detector 130 can detect the reflected and/orscattered light and can send an electrical signal indicative of thelight to controller 140 (step 163 of process 151).

Light source 102 can, additionally or alternatively, emit light towardsreference 108 (step 165 of process 151). Reference 108 can reflect lighttowards optics 194 (step 167 of process 151). Reference 108 can include,but is not limited to, a mirror, a filter, and/or a sample with knownoptical properties. Optics 194 can redirect, collimate, focus, and/ormagnify light towards detector 130 (step 169 of process 151). Detector130 can measure light reflected from reference 108 and can generate anelectrical signal indicative of this reflected light (step 171 ofprocess 151). Controller 140 can be configured to receive both theelectrical signal indicative of light reflected/scattered from sample120 and the electrical signal indicative of light reflected fromreference 108 from detector 130. Controller 140 (or another processor)can determine one or more properties of the sample from the electricalsignals (step 173 of process 151).

In some examples, when the system is measuring the one or moresubstances in the sample and in the reference, light emitted from thelight source 102 can reflect off a surface of the sample back intosystem 100. Light reflected off the exterior interface of the system(e.g., interface where the system contacts the sample) can be referredto as interface reflected light 184. In some examples, interfacereflected light 184 can be light emitted from light source 102 that hasnot reflected off sample 120 or reference 108 and can be due to lightscattering. Since interface reflected light 184 can be unwanted,absorber or light blocker 192 can prevent interface reflected light 184from being collected by optics 194 and light collection optics 116,which can prevent interface reflected light 184 from being measured bydetector 130.

FIG. 2 illustrates a cross-sectional view of an exemplary systemconfigured to determine one or more properties of a sample according toexamples of the disclosure. System 200 can be close to, touching,resting on, or attached to sample 220. Sample 220 can include one ormore locations, such as location 257 and location 259. System 200 caninclude a light source 202. Light source 202 can be configured to emitlight 250. Light source 202 can be any source capable of generatinglight including, but not limited to, a lamp, laser, light emitting diode(LED), organic light emitting diode (OLED), electroluminescent (EL)source, quantum dot (QD) light emitter, super-luminescent diode,super-continuum source, fiber-based source, or a combination of one ormore of these sources. In some examples, light source 202 can be capableof emitting a single wavelength of light. In some examples, light source202 can be capable of emitting a plurality of wavelengths of light. Insome examples, light source 202 can be any tunable source capable ofgenerating a SWIR signature. In some examples, a plurality of lightsources can be included in the system with each light source 202emitting a different wavelength range of light (e.g., different colorsin the spectrum). In some examples, light source 202 can include a III-Vmaterial, such as Indium Phosphide (InP), Gallium Antimonide (GaSb),Gallium Arsenide Antimonide (GaAsSb), Aluminum Arsenide (AlAs), AluminumGallium Arsenide (AlGaAs), Aluminum Indium Arsenide (AlInAs), IndiumGallium Phosphide (InGaP), Indium Gallium Arsenide (InGaAs), IndiumArsenide Antimonide (InAsSb), Indium Phosphide Antimonide (InPSb),Indium Arsenide Phosphide Antimonide (InAsPSb), and Gallium IndiumArsenide Antimonide Phosphide (GaInAsSbP).

System 200 can include input region 282 located close to or near sample220 or an external surface of the system. Input region 282 can includeone or more transparent components including, but not limited to, awindow, an optical shutter, or a mechanical shutter.

Light 250 can exit system 200 through input region 282. In someexamples, light 250 can be a collimated beam. Light that exits system200 and travels through sample 220 to location 257 can be referred to aslight 252. Light 252 can be incident on location 257 at any angleincluding, but not limited to, 45°. In some examples, light 252 can havean angle of incidence at location 257 between 20° to 30°. In someexamples, light 252 can have an angle of incidence at location 257 of35°. Location 257 can include one or more properties of sample 220.Light 252 can be partially absorbed prior to reaching location 257, atlocation 257, and/or after being partially reflected and/or scattered atlocation 257, and can be referred to as light 254. In some examples,light 254 can be formed by light transmitting through sample 220. Light254 can penetrate through sample 220 and can enter system 200 atlocation 213 of optic 210. In some examples, optic 210 can be in contactor near sample 220. In some examples, optic 210 can be any type ofoptical component such as a window. In some examples, optic 210 can beany optical component, such as a lens, capable of changing the behaviorand properties of the incoming light. In some examples, optic 210 caninclude a transparent material. Optic 210 can include a plurality oflocations, including location 213 and location 217, where light can beallowed to enter. In some examples, optic 210 can be a lens configuredwith a large aperture (e.g., an aperture larger than the size of theincoming light beam) and a short focal length (e.g., the focal lengthcan be such that a sample within 10 mm proximity to the system is infocus). In some examples, optic 210 can be a Silicon lens or a lensincluding silicon dioxide.

System 200 can include optics to magnify or reimage the incoming lightbeam. The optics in system 200 can be capable of reimaging the opticalpaths including path lengths, angles of incidences, and exit locationsto another plane closer to the detector array 230. To reduce thedifferences in any fluctuations, drifts, and/or variations between alight path (e.g., light 252 or light 253) penetrating through sample 220and a light path reflecting off a reference 222 (e.g., a reflector),system 200 can share the optics between the two different light paths.System 200 can include optic 210, optic 216, and/or optic 218 forreimaging both light that has penetrated and light that has notpenetrated through sample 220. In some examples, optic 216 and optic 218can be configured such that a reimage of the incident optical paths atthe exterior interface of the system (e.g., interface where the systemcontacts the sample) can be reimaged onto another plane (e.g., planewhere detector array 230 is located) without magnification. In someexamples, optic 216 and optic 218 can be configured such that amagnification, such as a 2.5×-5× magnification, is introduced into theimage.

Light 254 can be transmitted through optic 216 and optic 218 and can beincident on optic 223. Optic 223 can be included in optics unit 229.Optics unit 229 can comprise a plurality of optics, such as optic 223and optic 227, attached to a substrate. In some examples, the optics canbe of any type and can include any type of material conventionally usedin optics. In some examples, two or more of the optics can have the sameoptical (e.g., reflectance, refractive index, and transparency range)and/or geometric properties (e.g., curvature/focal length or pitch). Oneskilled in the art would appreciate that the same optical properties andthe same geometric properties can include tolerances that result in a15% deviation. In some examples, optics unit 229 can be coupled to oneor more aperture layers. In some examples, optics unit 229 can becoupled to a patterned aperture layer, such as an aperture layerincluding locations between adjacent optics are opaque to prevent lightmixing.

Light 254 can be transmitted through optic 223, and optic 223 canconverge light 254 to be detected by detector pixel 233 included indetector array 230. In some examples, optic 223 can converge light 254to a center location (not shown) or an edge location of the detectorpixel. Detector array 230 can include one or more detector pixels, suchas detector pixel 233, detector pixel 235, and detector pixel 237,disposed on a substrate. A detector pixel can include one or moredetector elements with a common footprint (e.g., same size and shape). Adetector element can be an element designed to detect the presence oflight and can individually generate a signal representative of thedetected light. In some examples, at least one detector pixel can beindependently controlled (e.g., measured, observed, or monitored) fromother detector pixels in detector array 230. In some examples, at leastone detector pixel can be capable of detecting light in the short-waveinfrared (SWIR) range. In some examples, at least one detector pixel canbe a SWIR detector capable of operating between 2.0-2.5 μm. In someexamples, at least one detector pixel can be a HgCdTe, InSb, or InGaAsbased detector. In some examples, at least one detector pixel can beassociated with a particular sample position and/or angle of lightincident on a surface of system 200. Detector pixel 233 can detect light254 and can generate an electrical signal indicative of the propertiesof detected light 254. Detector array 230 can transmit the electricalsignal to controller 240, and controller 240 can process and/or storethe electrical signal.

System 200 can determine one or more properties of sample 220 byutilizing the information from light reflected from the sample inconjunction with information from light reflecting off a reference 222,such as a reflector. Light source 202 can emit light 264. Light 264 canbe directed at reference 222. Reference 222 can include any type ofmaterial capable of at least partially reflecting incident light.Exemplary reflective materials can include, but are not limited to,Titanium (Ti), Cobalt (Co), Niobium (Nb), Tungsten (W), Nickel Chrome(NiCr), Titanium Tungsten (TiW), Chrome (Cr), Aluminum (Al), Gold (Au),and Silver (Ag). In some examples, reflective materials can include oneor more dielectric layers. One or more properties (e.g., thickness) ofreference 222 can be determined based on the wavelength of light, typeof material, and/or composition of reference 222. In some examples, thesize and shape of reference 222 can be configured to be larger or thesame size and/or shape of light beam of light 264. One skilled in theart would appreciate that the same size and shape can include tolerancesthat result in a 15% deviation. In some examples, the optical and/orphysical properties of reference 222 can be such that the reflectivityof light 264 is greater than 75%. In some examples, the optical and/orphysical properties of reference 222 can be such that the reflectivityof light 264 can be greater than 90%. In some examples, the size andshape of reference 222 can be such that less than 15% of light 264 isallowed to transmit through the reference 222 and light 264 is preventedfrom reaching sample 220. In some examples, the reference 222 can beconfigured to reflect light 264 as a specular reflection. In someexamples, reference 222 can be a spectroscopically neutral blocker. Insome examples, the reference signal can include chopping light 264between light 252 entering sample 220 and light 264 incident onreference 222. Although FIG. 2 illustrates reference 222 as located atthe exterior interface of the system (e.g., interface where the systemcontacts the sample), examples of the disclosure can include thereference located at other locations including, but not limited to, aninterior wall of the system, a side of the optics, and the like.

Light 264 can reflect off reference 222 towards optic 216. Light 264 canbe transmitted through optic 216 towards optic 218. Light 264 can betransmitted through optic 218 and can be incident on optic 219, includedin optics unit 229. Optic 219 can be any type of optics configured forspreading out the incoming light beam. In some examples, optic 219 canbe a negative lens, which can be a lens with a focal length that isnegative. In some examples, optic 219 can be a prism. In some examples,optic 219 can include a prism wedge angled for each detector pixel indetector array 230. In some examples, optic 219 can be a beamsplitter.In some examples, optic 219 can be configured to spread out or dividelight into multiple beams, such as light 266 and light 267. In someexamples, optic 219 can spread out light such that each light beam canbe directed to a different detector pixel in detector array 230. In someexamples, optic 219 can uniformly spread out light such that theproperties of each light beam can be the same. One skilled in the artwould appreciate that the same properties can include tolerances thatresult in a 15% deviation. In some examples, optic 219 can spread outlight such that intensities of at least two light beams are different.In some examples, optic 219 can comprise multiple optics. In someexamples, the size and/or shape of optic 219 can be based on the numberof detector pixels that light is spread to, the properties of the one ormore light beams exiting optic 219, or both. In some examples, anaperture layer can be coupled to optic 219 to control the propertiesand/or direction of light exiting optic 219. In some examples, optic 219or system 200 can be configured such that light that reflects off asurface of the sample back into the system (i.e., light that has notpenetrated through sample 220) is prevented from being incident on optic219, although stray light or background light can be incident on optic219.

Light 264 can transmit through optic 219 to form light 266. Light 266can be incident on detector pixel 233. Detector pixel 233 can detectlight 266 and can generate an electrical signal indicative of theproperties of detected light 266. In some examples, the number ofdetector pixels configured to detect a light beam can be different fordifferent light beams. For example, light 255 can be detected by twodetector pixels (e.g., detector pixel 235 and detector pixel 237), whilelight 254 can be detected by one detector pixel (e.g., detector pixel233). The electrical signal can be transmitted from detector array 230to controller 240. Controller 240 can process and/or store theelectrical signal. Controller 240 can utilize the signal informationmeasured from light 254 to determine the reflectivity or one or moresample properties along the light path directed to location 257 and canutilize the signal information from light 266 to detect any fluctuationsor drift in light source 202 and/or detector array 230. Using any of theabove discussed methods, controller 240 can process the electricalsignal and the signal information to determine the one or moreproperties of sample 220.

The same components in system 200 can be used for measurements at otherlocations, such as location 259, in sample 220. Light 252 that is notabsorbed or reflected along the light path directed to location 257 canbe referred to as light 253. Light 253 can be incident on location 259and can reflect and/or scatter into system 200 as light 255. In someexamples, the angle of incidence of light 255 at the surface of system200 can be different from the angle of incidence of light 254. Light 255can enter system 200 through optic 210 at location 217. Light 255 can betransmitted through optic 216 and optic 218 and can be incident on optic227, included in optics unit 229. Light 255 can be transmitted throughoptic 227, and optic 227 can converge, redirect, collimate, focus,and/or magnify light such that light 255 is detected by detector pixel235 and detector pixel 237, included in detector array 230. Detectorpixel 235 and detector pixel 237 can detect light 255 and can generateelectrical signals indicative of the properties of detected light 255.In some examples, optic 227 can converge, redirect, collimate, focus,and/or magnify light such that light 255 is incident on a centerlocation or an edge location of the detector pixel. Any number ofdetector pixels can be configured to detect a light beam. Detector array230 can transmit the electrical signal to controller 240. Controller 240can process and/or store the electrical signal.

Controller 240 can utilize the signal information measured from light255 to determine one or more properties of sample 220 and can utilizethe signal information from light 267 to detect any fluctuations ordrift in light source 202 and/or detector array 230. In some examples,controller 240 can detect light 266 incident on detector pixel 233 andlight 267 incident on detector pixel 235 and/or detector pixel 237simultaneously without the need for separate measurements. In someexamples, location 257 and location 259 can have the same depth from thesurface of sample 220 or the exterior interface of the system (e.g.,interface where the system contacts the sample). One skilled in the artwould appreciate that the same depth can include tolerances that resultin a 15% deviation. In some examples, location 257 and location 259 canhave different depths from the surface of sample 220. Controller 240 canmeasure the reflectivity, refractive index, density, concentration,scattering coefficient, scattering anisotropy, or absorbance at bothlocation 257 and location 259 and can average the values.

Although the figure and discussion above relates to two locations in thesample, examples of the disclosure can include any number of locationsand are not limited to one or two locations. In some examples, light canbe incident on the multiple locations at the same angle of incidence. Insome examples, the light source can be configured to generate one lightbeam exiting the system that results in multiple input light beamsreflected and/or scattered back into the system. In some examples, thesystem can be configured with one or more light sources that emit lightat locations with different angles of incidence, where the light can beemitted at the same time or at different times.

In some examples, system 200 can further include a light blocker 292.Light blocker 292 can include any material capable of absorbing orblocking light. In some examples, light blocker 292 can include anymaterial (e.g., an anti-reflection coating) that prevents incident lightfrom reflecting. That is, light blocker 292 can prevent unwanted lightfrom reaching and being measured by detector array 230. In someexamples, light blocker 292 can include any material that reflects atwavelengths different from the detection wavelengths of detector array230.

As illustrated in the figure, system 200 can include a plurality ofoptics and a plurality of detector pixels, where each optic can beassociated to one or a plurality of detector pixels. Eachoptics-detector pixel pair can be associated with an optical path insample 220. In some examples, the association can be one optics-detectorpixel pair to one optical path in sample 220. For example, optic 223 anddetector pixel 233 can be associated with the optical path from light254, and optic 227 and detector pixel 237 can be associated with theoptical path from light 255. Since controller 240 can associate detectorpixel 233 and detector pixel 237 with different locations (e.g.,location 257 and location 259) and/or different light paths in sample220, controller 240 can discern differences in path lengths, depths ofpenetration, angles of incidence, exit locations, and/or exit angles.

FIG. 3 illustrates a cross-sectional view of an exemplary systemconfigured to determine one or more properties of a sample according toexamples of the disclosure. System 300 can be close to, touching,resting on, or attached to a surface of sample 320. Sample 320 caninclude one or more locations, such as location 357 and location 359. Insome examples, the one or more locations can be associated with one ormore scattering events.

System 300 can include a light source 302. Light source 302 can beconfigured to emit light 350. Light source 302 can be configured to emitlight 350. Light source 302 can be any source capable of generatinglight including, but not limited to, a lamp, laser, light emitting diode(LED), organic light emitting diode (OLED), electroluminescent (EL)source, quantum dot (QD) light emitter, super-luminescent diode,super-continuum source, fiber-based source, or a combination of one ormore of these sources. In some examples, light source 302 can be capableof emitting a single wavelength of light. In some examples, light source302 can be capable of emitting a plurality of wavelengths of light. Insome examples, light source 302 can be any tunable source capable ofgenerating a SWIR signature. In some examples, a plurality of lightsources can be included in the system with each light source 302emitting a different wavelength range of light (e.g., different colorsin the spectrum). In some examples, light source 302 can include a III-Vmaterial, such as Indium Phosphide (InP), Gallium Antimonide (GaSb),Gallium Arsenide Antimonide (GaAsSb), Aluminum Arsenide (AlAs), AluminumGallium Arsenide (AlGaAs), Aluminum Indium Arsenide (AlInAs), IndiumGallium Phosphide (InGaP), Indium Gallium Arsenide (InGaAs), IndiumArsenide Antimonide (InAsSb), Indium Phosphide Antimonide (InPSb),Indium Arsenide Phosphide Antimonide (InAsPSb), and Gallium IndiumArsenide Antimonide Phosphide (GaInAsSbP).

System 300 can also include an input region 382 located close to or nearsample 320 or an external surface of the system. Input region 382 caninclude one or more transparent components including, but not limitedto, a window, optical shutter, or mechanical shutter.

Light 350 can exit system 300 through input region 382. In someexamples, light 350 can be a collimated beam. Light that exits system300 and travels through sample 320 to location 357 can be referred to aslight 352. Light 352 can be incident on location 357 at any angleincluding, but not limited to, 45°. In some examples, light 352 can havean angle of incidence at location 357 between 20° to 30°. In someexamples, light 352 can have an angle of incidence at location 357 of35°. Location 357 can include one or more properties of sample 320.Light 352 can be partially absorbed prior to reaching location 357, atlocation 357, and/or after being partially reflected and/or scattered atlocation 357, and can be referred to as light 354. In some examples,light 354 can be formed by light transmitting through sample 320. Light354 can penetrate through sample 320 and can enter system 300 atlocation 313 of optic 310. In some examples, optic 310 can be in contactor near sample 320. Optic 310 can be any type of optical component, suchas a lens, capable of changing the behavior and properties of theincoming light. Optic 310 can include a plurality of locations, such aslocation 313 and location 317, where light exiting sample 320 is allowedto enter into system 300. In some examples, optic 310 can include atransparent material. In some examples, optic 310 can be a lensconfigured with a large aperture (e.g., an aperture larger than the sizeof the incoming light beam) and a short focal length (e.g., the focallength can be such that a sample 220 within 10 mm proximity to system isin focus). In some examples, optic 310 can be a Silicon lens or a lensincluding silicon dioxide.

System 300 can include optics, such as optic 316 and optic 318. In someexamples, optic 316 and optic 318 can be objective lenses. An objectivelens is a lens capable of collecting incident light and magnifying thelight beam, while having a short focal length. Optic 316 can collectlight 354 and direct light 354 towards opening 385 included in aperturelayer 386. Aperture layer 386 can include one or more openings, such asopening 385 and opening 387, configured to allow light to transmitthrough. Aperture layer 386 can be capable of selecting light with oneor more specific path lengths, angles of incidence, or both andrejecting or attenuating light with other path lengths or angles ofincidence. Selection and rejection of light based on path length, angleof incidence, or both can be optimized by adjusting the aperture size(i.e., the size of an opening in the aperture layer). The selected light(i.e., light with one or more specific path lengths, angles ofincidence, or both) can be in focus when it reaches an opening in theaperture layer, and rejected light can be out of focus. Light that isout of focus can have a beam size that is larger than the aperture size,can have an angle of incidence that is outside the collection range, orboth, and therefore can be rejected. Light that is in focus can have alight beam that is within a range of path lengths and range ofcollection angles, and therefore can be allowed to transmit through theaperture layer.

Light 354 exiting opening 385 in aperture layer 386 can be transmittedthrough optic 318 and can be incident on optic 323. Optic 323 can beincluded in optics unit 39. Optics unit 39 can comprise a plurality ofoptics, such as optic 323 and optic 327, attached to a substrate. Insome examples, the optics can be of any type and can include any type ofmaterial conventionally used in optics. In some examples, two or more ofthe optics can have the same optical and/or geometric properties. Oneskilled in the art would appreciate that the same optical properties andthe same geometric properties can include tolerances that result in a15% deviation. In some examples, optics unit 39 can be coupled to one ormore aperture layers. In some examples, optics unit 39 can be coupled toa patterned aperture layer, such as an aperture layer includinglocations between adjacent optics are opaque to prevent light mixing.

Light 354 can be transmitted through optic 323 and can be incident ondetector pixel 333 included in detector array 330. Detector array 330can include a plurality of detector pixels, such as detector pixel 333,detector pixel 335, and detector pixel 337. A detector pixel can includeone or more detector elements with a common footprint (e.g., same sizeand shape). A detector element can be an element designed to detect thepresence of light and can individually generate a signal representativeof the detected light. In some examples, at least one detector pixel canbe independently controlled (e.g., measured, observed, or monitored)from other detector pixels in detector array 330. In some examples, atleast one detector pixel can be capable of detecting light in the SWIRrange. In some examples, at least one detector pixel can be a SWIRdetector capable of operating between 1.5-2.5 μm. In some examples, atleast one detector pixel can be a HgCdTe, InSb, or InGaAs baseddetector. In some examples, at least one detector pixel can beassociated with a particular sample position and/or angle of lightincident on a surface of system 300. Detector pixel 333 can detect light354 and can generate an electrical signal indicative of the propertiesof the detected light 354. Detector array 330 can transmit theelectrical signal to controller 340, and controller 340 can processand/or store the electrical signal.

System 300 can determine the one or more properties in sample 320 byutilizing the information from light penetrating through sample 320 (andreflecting off locations within the sample) in conjunction with theinformation from light reflecting off reference 322. Light source 302can emit light 364. Light 364 can be directed at reference 322.Reference 322 can include any type of material capable of at leastpartially reflecting light. Exemplary reflective materials can include,but are not limited to, Ti, Co, Nb, W, NiCr, TiW, Cr, Al, Au, and Ag. Insome examples, reflective materials can include one or more dielectriclayers. One or more properties (e.g., thickness) of reference 322 can bedetermined based on the wavelength of light, type of material, and/orcomposition of the reference. In some examples, the size and shape ofreference 322 can be configured to be larger or the same size and/orshape of light 364. One skilled in the art would appreciate that thesame size and same shape can include tolerances that result in a 15%deviation. In some examples, the optical and/or physical properties ofreference 322 can be such that the reflectivity of light 364 is greaterthan 75%. In some examples, the optical and/or physical properties ofreference 322 can be such that the reflectivity of light 364 is greaterthan 90%. In some examples, the size and shape of reference 322 can besuch that less than 15% of light 364 is allowed to transmit throughreference 322 and light 364 is prevented from reaching sample 320. Insome examples, reference 322 can be configured to reflect light 364 as aspecular reflection. In some examples, reference 322 can be aspectroscopically neutral blocker. In some examples, the referencesignal can include chopping light 364 between sample 320 and reference322.

Light 364 can reflect off reference 322 towards optic 316. Light 364 canbe transmitted through optic 316 towards aperture layer 386. Aperturelayer 386 can be configured with opening 389, whose size and shape canbe configured to allow light 364 to transmit through. Light 364 exitingopening 389 can be incident on optic 318. Light 364 can be transmittedthrough optic 318 and be incident on optic 319. Optic 319 can be anytype of optics configured for spreading out the incoming light beam. Insome examples, optic 319 can be a negative lens, which is a lens with afocal length that is negative. In some examples, optic 319 can be aprism. In some examples, optic 319 can include a prism wedge angled foreach detector pixel in detector array 330. In some examples, optic 319can be a beamsplitter. In some examples, optic 319 can be configured tospread out or divide light into multiple light beams, such as light 366and light 367. In some examples, optic 319 can spread out light suchthat each light beam is directed to a different detector pixel ondetector array 330. In some examples, optic 319 can uniformly spread outlight such that one or more properties of each light beam are the same.One skilled in the art would appreciate that the same properties caninclude tolerances that result in a 15% deviation. In some examples,optic 319 can spread out the light beam such that intensities of atleast two light beams are different. In some examples, optic 319 cancomprise multiple optics. In some examples, the size and/or shape ofoptic 319 can be based on the number of detector pixels and/or theproperties of the one or more light beams exiting optic 319. In someexamples, an aperture layer can be coupled to optic 319 to control theproperties and/or direction of light exiting optic 319.

Light 364 can be transmitted through optic 319 to form light 366. Light366 can be incident on detector pixel 333. Detector pixel 333 can detectlight 366 and can generate an electrical signal indicative of theproperties of detected light 366. In some examples, the number ofdetector pixels configured to detect a light beam can be different fordifferent light beams. For example, light 355 can be detected by twodetector pixels (e.g., detector pixel 335 and detector pixel 337), whilelight 354 can be detected by one detector pixel (e.g., detector pixel233). The electrical signal can be transmitted from detector array 330to controller 340. Controller 340 can process and/or store theelectrical signal. Controller 340 can utilize the signal informationmeasured from light 354 to determine the reflectivity or one or moreproperties along the light path directed to location 357 and can utilizethe signal information from light 366 to detect any fluctuations ordrift in light source 302 and/or detector array 330. Using any of theabove discussed methods, the controller 340 can process both theelectrical signal and the signal information to determine the one ormore properties of sample 320.

The same components can be used for measurements at other locations,such as location 359, in sample 320. Light 352 that is not absorbed orreflected along the light path directed to location 357 can be referredto as light 353. Light 353 can be incident on location 359 and canreflect and/or scatter into system 300 as light 355. In some examples,the angle of incidence of light 355 at the surface of system 300 can bedifferent from the angle of incidence of light 354. Light 355 can entersystem 300 through optic 310 at location 317. Light 355 can betransmitted through optic 316 and can be incident on aperture layer 386.Aperture layer 386 can include opening 387 configured to allow light 355(and any light with the same path length, angle of incidence, or both)to transmit through. One skilled in the art would appreciate that thesame path length and same angle of incidence can include tolerances thatresult in a 15% deviation. In some examples, since light reflected fromlocation 357 can have a path length different from light reflected fromlocation 359, aperture layer 386 can include multiple openings withdifferent sizes and/or shapes to account for the different properties(e.g., path length and angle of incidence) of the optical paths. Forexample, opening 385 can be configured with a size and shape based onthe path length and angle of incidence of light 354, and opening 387 canbe configured with a size and shape based on the path length and angleof incidence of light 355. Light 355 can be transmitted through opening387 in aperture layer 386, can be transmitted through optic 318, and canbe incident on optic 327 included in optics unit 39. Light 355 can betransmitted through optic 327, and optic 327 can converge, redirect,collimate, focus, and/or magnify light such that light 355 is detectedby detector pixel 335 and detector pixel 337. Detector pixel 335 anddetector pixel 337 can detect light 355 and can generate an electricalsignal indicative of the properties of detected light 355. The detectorarray 330 can transmit the electrical signal to controller 340, andcontroller 340 can process and/or store the electrical signal.

Controller 340 can utilize the signal information measured from light355 to determine one or more properties of sample 320 and can utilizethe signal information from light 367 to detect any fluctuations ordrift in light source 302 and/or detector array 330. Controller 340 canprocess both of the collections of signal information to determine oneor more properties along the light path directed to location 359 locatedin sample 320. In some examples, controller 340 can detect light 366incident on detector pixel 333 and light 367 incident on detector pixel335 and detector pixel 337 simultaneously without the need for separatemeasurements. In some examples, location 357 and location 359 can havethe same depth from the surface of sample 320. One skilled in the artwould appreciate that the same depth can include tolerances that resultin a 15% deviation. In some examples, location 357 and location 359 canhave different depths from the surface of sample 320. Controller 340 canmeasure the reflectivity, refractive index, density, concentration,scattering coefficient, scattering anisotropy, or absorbance at bothlocation 357 and location 359 and can average the values.

Although the figure and discussion above relates to two locations in thesample, examples of the disclosure can include any number of locationsand are not limited to one or two locations. In some examples, light canbe incident on the multiple locations at the same angle of incidence. Insome examples, the light source can be configured to generate one lightbeam exiting the system that results in multiple input light beamsreflected and/or scattered back into the system. In some examples, thesystem can be configured with one or more light sources that emit lightat locations with different angles of incidence, where the light can beemitted at the same time or at different times.

As illustrated in the figure, system 300 can include a plurality ofopenings in the aperture, a plurality of optics, and a plurality ofdetector pixels, where each opening and optics can be coupled to adetector pixel. Each opening/optics/detector pixel trio can beassociated with an optical path in sample 320. In some examples, theassociation can be one opening-optics-detector pixel trio to one opticalpath in the sample 320. For example, opening 385, optic 323, anddetector pixel 333 can be associated with the optical path from light354. Similarly, opening 387, optic 327, and detector pixel 337 can beassociated with the optical path from light 355. Since controller canassociate detector pixel 333 and detector pixel 337 with differentlocations (e.g., location 357 and location 359) in sample 320 anddifferent depths or path lengths, the controller 340 can discerndifferences in path lengths, depths of penetration, angles of incidence,exit locations, and/or exit angles.

In some examples, system 300 can further include a light blocker 392.Light blocker 392 can include any material capable of absorbing orblocking light. In some examples, light blocker 392 can include anymaterial (e.g., an anti-reflection coating) that prevents incident lightfrom reflecting. In some examples, light blocker 392 can include anymaterial that reflects at wavelengths different from the detectionwavelengths of detector array 330.

FIG. 4A illustrates a cross-sectional view of an exemplary portion of asystem configured for resolving multiple angles of incidence on a samplesurface with two-layers of optics according to examples of thedisclosure. System 400 can be close to, touching, resting on, orattached to sample 420. Sample 420 can include one or more locations,such as location 457. In some examples, the one or more locations can beassociated with one or more scattering events. System 400 can beconfigured to reimage the optical paths in sample 420. For example,system 400 can be configured to reimage the angles of incident light andthe exit locations to another plane (e.g., a plane located closer todetector array 430). Reimaging of the optical paths can be performedusing one or more layers of optics. System 400 can include two layers ofoptics, for example. Located below (i.e., opposite the surface of sample420) the layers of optics can be a detector array 430, and thetwo-layers of optics can be supported by support 414. Located betweenthe two layers of optics can be air, a vacuum, or any medium with arefractive index that contrasts the refractive index of the optics.Although the figures illustrates a system including two-layers ofoptics, examples of the disclosure can include, but are not limited to,any number of layers of optics including one layer or more than twolayers.

System 400 can include light sources 402. Light sources 402 can beconfigured to emit light 450. Light sources 402 can be any sourcecapable of generating light including, but not limited to, a lamp,laser, light emitting diode (LED), organic light emitting diode (OLED),electroluminescent (EL) source, quantum dot (QD) light emitter,super-luminescent diode, super-continuum source, fiber-based source, ora combination of one or more of these sources. In some examples, lightsources 402 can be capable of emitting a single wavelength of light. Insome examples, light sources 402 can be capable of emitting a pluralityof wavelengths of light. In some examples, light sources 402 can be anytunable source capable of generating a SWIR signature. In some examples,each of light sources 402 can emit a different wavelength range of light(e.g., different colors in the spectrum). In some examples, lightsources 402 can include a III-V material, such as Indium Phosphide(InP), Gallium Antimonide (GaSb), Gallium Arsenide Antimonide (GaAsSb),Aluminum Arsenide (AlAs), Aluminum Gallium Arsenide (AlGaAs), AluminumIndium Arsenide (AlInAs), Indium Gallium Phosphide (InGaP), IndiumGallium Arsenide (InGaAs), Indium Arsenide Antimonide (InAsSb), IndiumPhosphide Antimonide (InPSb), Indium Arsenide Phosphide Antimonide(InAsPSb), and Gallium Indium Arsenide Antimonide Phosphide (GaInAsSbP).

Light from light sources 402 can be combined using integrated tuningelements 404, optical traces (not shown), and one or more multiplexers(not shown). In some examples, integrated tuning elements 404, theoptical traces, and the multiplexer(s) can be disposed on a substrate442 or included in a single optical platform, such as a siliconphotonics chip. System 400 can also include a thermal management unit401 for controlling, heating, or cooling the temperature of lightsources 402. Coupled to one or more multiplexers can be outcouplers 409.Outcouplers 409 can optionally be configured to focus, collect,collimate, and/or condition (e.g., shape) the light beam from themultiplexer(s) towards optic 416. In some examples, outcouplers 409 canbe configured as a single mode waveguide that directs a well-defined(i.e., directional) light beam towards optic 416. In some examples,light 450 from outcouplers 409 can be a light beam with any suitableshape (e.g., conical, cylindrical, etc.). In some examples, light 450from outcouplers 409 can become totally internally reflected (TIR) and“trapped” between substrate 442 and one or both of the layers of optics.Optic 416 can receive light 450 and can collimate and/or tilt the lightbeam towards one or more locations in sample 420. In some examples,optic 416 can include a bottom surface (i.e., surface facing outcouplers409) that is flat (or within 10% from flat) and a top surface (i.e.,surface facing away from outcouplers 409) that is convex. Light that isemitted from light sources 402, collimated by outcouplers 409,transmitted through optic 416, and then exits system 400 can be referredto as light 452.

In some examples, outcouplers 409 can be coupled to a waveguideincluding in a junction. FIG. 4B illustrates an exemplary junctioncoupled to the light sources according to examples of the disclosure.Junction 403 can be configured to split or divide light emitted fromlight sources 402, where a portion of light can be directed to waveguide405 and a portion of light can be directed to waveguide 407. Waveguide405 can be coupled to an outcoupler 409, which can direct light tosample 420. Waveguide 407 can also be coupled to an outcoupler 409,which can direct light to reference 422. In some examples, light fromlight sources 402 can split at junction 403, and light can be splitequally among waveguide 405 and waveguide 407. In some examples,junction 403 can be an asymmetric y-junction, and light can be splitsuch that the intensity of light through waveguide 405 is greater thanthe intensity of light through waveguide 407.

In some examples, the height and width of waveguide 405, waveguide 407,or both can be configured based on the size and shape of the light beamand divergence properties. For example, for an elliptical light beam,the aspect ratio of waveguide 405 can be configured to be greater thanone. In some examples, the aspect ratio of waveguide 405 can be equal toone, and the light beam can be circular in shape. In some examples, theaspect ratio of waveguide 405 can be less than one. In some examples,the height of the waveguide can be less than the width of the waveguidesuch that the light beam diverges asymmetrically.

As discussed above, reference switching can include alternating betweentransmitting light to sample 420 and transmitting light to reference422. While this switching can be performed using mechanical movingparts, examples of the disclosure can include non-moving parts thatblock light, such as diode 411. Diode 411 can be coupled to a source413, which can be configured to supply a current through waveguide 405.With a current through waveguide 405, the electrons in the current canabsorb the photons in light traveling through waveguide 405, which canprevent light from being output from waveguide 405. Light throughwaveguide 407 can also be modulated with another diode 411 coupled toanother source 413, which can be configured to supply a current throughwaveguide 407. In some examples, waveguide 405 and/or waveguide 407 caninclude be configured such that the current passes through multiplelocations along the waveguide, as illustrated in FIG. 4C. By passingcurrent through multiple locations along the waveguide, a lower currentsupplied from source 413 may be needed to block light, which can lead tolower power consumption. Although FIG. 4B illustrates two diodes (e.g.,diode 411 coupled to waveguide 405 and another diode 411 coupled towaveguide 407), examples of the disclosure can include any number ofdiodes.

Referring back to FIG. 4A, light 452 can be directed at sample 420 andcan be incident on location 457. A portion of light 452, referred to aslight 454, can reflect back and/or scatter to system 400 with an angleof incidence θ₁. In some examples, light 452 exiting system 400 can be acollimated light beam, where one or more scattering events can occuralong the light path directed to location 457 and can lead to light 454becoming a scattered light beam. Light 454 can enter system 400 and canbe incident on optic 418, included in optics unit 410. In some examples,light 454 can be a collimated light beam.

System 400 can include one or more optics units. In some examples, theoptics units can have one or more different functionalities and/or caninclude one or more different materials. For example, optics unit 410can change the general direction of light, while optics unit 429 canfocus the light. In some instances, optics unit 410 can include sapphirelenses, while optics unit 429 can include silicon lenses.

Optics unit 410 can include one or more optics (e.g., lenses,micro-optics, or micro-lens) configured to collect incident light,condition the size and shape of the light beam, and/or focus incidentlight. For example, optic 418 can collect light 454 incident on system400 with an angle of incidence θ₁. Optic 418 can change the angle (i.e.,redirect the light beam) of light 454 such that light 454 is directedtowards the optics unit 429 and has an angle of incidence on the opticsunit 429 less than the angle of incidence θ₁. In some examples, themedium between optics unit 410 and optics unit 429 can be configuredwith a refractive index such that the change in angle (i.e., bending) oflight 454 decreases. In some examples, the medium can bemulti-functional and can include a conformal material that providesmechanical support. In some examples, optic 418 can focus light 454 atleast partially. In some examples, optics unit 410 can preferentiallycollect light rays included in light 454 with an angle of incidencewithin a range of collection angles. In some examples, optics unit 410can include plurality of silicon lenses. In some examples, optics unit410 can include one or more optics. Although FIG. 4A illustrates opticsunit 410 attached to support 414, examples of the disclosure can includeoptics unit 410 attached to or coupled to optics unit 429 throughmechanical features etched into optics unit 410, optics unit 429, orboth. In some examples, at least two optics included in optics unit 410can have different geometric properties. A detailed discussion of theproperties of the optics in optics unit 410 is provided below.

System 400 can also include an aperture layer 486. Aperture layer 486can include an opening 487 configured to allow light 454 (or any lightwith the same angle of incidence θ₁) to transmit through. One skilled inthe art would appreciate that the same angle of incidence can includetolerances that result in a 15% deviation. Light 454 that has beentransmitted through opening 487 can be directed towards optic 423,included in optics unit 429. Optics unit 429 can comprise a plurality ofoptics, such as optic 423 and optic 427, attached to a substrate. Insome examples, optic 423 and optic 427 can be any type of optics and caninclude any type of material conventionally used in optics. In someexamples, two or more of the optics in optics unit 429 can have the sameoptical and/or geometric properties. One skilled in the art wouldappreciate that the same optical properties and geometric properties caninclude tolerances that result in a 15% deviation. In some examples,optic 416 and the optics (e.g., optic 423 and optic 427) included in theoptics unit 429 can be disposed and/or formed on the same substrate. Insome examples, optic 416 and optics unit 429 can be fabricated at thesame time using lithography and the same etching process. Thelithographic patterning can define the alignments of the optics, whichcan reduce the number of alignment steps and the number of separatelyfabricated components. Although FIG.4A illustrates optics unit 429attached to support 414, examples of the disclosure can include opticsunit 429 attached to or coupled to optics unit 410 through mechanicalfeatures etched into optics unit 410, optics unit 429, or both. In someexamples, at least two optics included in optics unit 429 can havedifferent geometric properties. A detailed discussion of the propertiesof the optics in optics unit 429 is provided below.

Optic 423 can focus light 454 towards detector array 430. In someexamples, light 454 can undergo at least partial refraction from optic418. Optic 423 can recollimate light 454 and focus light 454. In someexamples, system 400 can be configured such that light 454 is turned byoptics unit 410 and focused by optics unit 429. In some examples, system400 can be configured such that light 454 is turned by both optics unit410 and optics unit 429. In some examples, optics unit 429 can include aplurality of silicon micro-optics.

Light 454 can transmit through optic 423 and can be detected by detectorpixel 433, included in detector array 430. Detector array 430 caninclude one or more detector pixels, such as detector pixel 433 anddetector pixel 437, disposed on a substrate. In some examples, thesubstrate can be a silicon substrate. A detector pixel can include oneor more detector elements with a common footprint (e.g., same size andshape). A detector element can be an element designed to detect thepresence of light and can individually generate a signal representativeof the detected light. In some examples, at least one detector pixel canbe independently controlled from other detector pixels in detector array430. In some examples, at least one detector pixel can be capable ofdetecting light in the SWIR range. In some examples, at least onedetector pixel can be a SWIR detector capable of operating between1.5-2.5 μm. In some examples, at least one detector pixel can be aHgCdTe, InSb, or InGaAs based detector. In some examples, at least onedetector pixel can be capable of detecting a position and/or angle oflight incident on a surface of the detector pixel. Detector pixel 433can be coupled to an integrated circuit, such as read-out integratedcircuit (ROIC) 441. Each circuit in ROIC 441 can store chargecorresponding to the detected light (or photons of light) on thedetector pixel in an integrating capacitor to be sampled and read out bya processor or controller (not shown). The stored charge can correspondto one or more optical properties (e.g., absorbance, transmittance, andreflectance) of light 454. In some examples, ROIC 441 can be fabricatedon a silicon substrate.

Another portion of light 452 incident on location 457 can reflect backinto system 400 with an angle of incidence θ₃, and can be referred to aslight 455. Light 455 can enter system 400 and can be incident on optic419, included in optics unit 410. Similar to optic 418, optic 419 cancollect incident light, condition the beam size and shape (e.g.,redirect the light beam), and/or focus incident light. Light 455 can betransmitted through opening 489 included in aperture layer 486. Light455 can be directed towards optic 427 included in optics unit 429. Optic427 can focus light 455 towards detector pixel 437 included in detectorarray 430. In some examples, system 400 can be configured such thatlight 455 is redirected by optics unit 410 and focused by optics unit429. In some examples, system 400 can be configured such that light 455is redirected by both optics unit 410 and optics unit 429.

As discussed earlier, system 400 can include a plurality of optics(e.g., optic 418 and optic 419) included in optics unit 410 and aplurality of optics (e.g., optic 423 and optic 427) included in opticsunit 429, where each of the optics can be coupled to a detector pixel(e.g., detector pixel 433 or detector pixel 437) included in detectorarray 430. Each first optics-second optics-detector pixel trio can beassociated with an optical path in sample 420. In some examples, theassociation can be one first optics-second optics-detector pixel trio toone optical path in sample 420. For example, optic 418, optic 423, anddetector pixel 433 can form a first optics-second optics-detector pixeltrio that is associated with the optical path from light 454. Similarly,optic 419, optic 427, and detector pixel 437 can form another firstoptics/second optics/detector pixel trio that is associated with theoptical path from light 455. In this manner, system 400 can be capableof reimaging and resolving the multiple optical paths with differentangles of incidence in sample 420, where each detector pixel in detectorarray 430 can be dedicated to a different optical path.

Although FIG. 4A illustrates detector pixel 433 and detector pixel 437as single detector pixels, each individually associated with optics,examples of the disclosure can include multiple detector pixelsassociated with the same optics and multiple optics associated with thesame detector pixel.

In some examples, system 400 can integrate the path lengths within arange of path lengths and associate the integrated path lengths with adetector pixel. By integrating the path lengths, different azimuthalangles can be resolved. Since there can be multiple sources (e.g.,incident light from a single scattering event or incident light frommultiple scattering events that change the path length) to optical pathsthat can have the same azimuthal angle, system 400 can resolve thedifferent sources. In some examples, resolving the different azimuthalangles can require a large format (e.g., more than a hundred detectorpixels) detector array.

In some examples, system 400 can be configured such that at least twofirst optics/second optics/detector pixel trios can resolve differentangles of incidence. For example, as discussed earlier, light 454 canhave an angle of incidence θ₁, and light 455 can have an angle ofincidence θ₃. In some examples, angle of incidence θ₁ can be differentfrom angle of incidence θ₃. In some examples, light 454 can have adifferent angle of incidence than light 455, but can have the same pathlength, for example. One skilled in the art would appreciate that thesame path length can include tolerances that result in a 15% deviation.System 400 can associate different detector pixels or the same detectorpixels in detector array 430 with different angles of incidence. Forexample, detector pixel 433 can be associated with angle of incidenceθ₁, and detector pixel 437 can be associated with angle of incidence θ₃.In some examples, the optical system can operate at infinite conjugate(i.e., infinite distance where the light rays collimate), so theproperties (e.g., focal length, working distance, aperture, pitch,fill-factor, tilt, and orientation) of the optics included in opticsunit 410 can be determined based on the angle of incidence.

In some examples, aperture layer 486 can be located between optics unit410 and optics unit 429. Aperture layer 486 can be located a focallength away from optics unit 410 and a focal length away from opticsunit 429. Additionally, system 400 can be configured with detector array430 located a focal length away from optics unit 429. This configurationcan require at least four layers in the stackup of system 400: opticsunit 410 on a first layer, aperture layer 486 on a second layer, opticsunit 429 on a third layer, and detector array 430 on a third layer.However, fewer numbers of layers may be desired for a system with athinner stackup, for example.

FIGS. 4D-4H illustrate cross-sectional views of exemplary opticsincluded in a system configured for resolving multiple optical paths ina sample according to examples of the disclosure. System 400 can includeone or more aperture layers located on the same layer as one or moreoptics or components in the system. As illustrated in FIG. 4D, aperturelayer 486 can be located on the same layer as optics unit 410. In someexamples, aperture layer 486 can be located on a surface of optics unit410. Although the figure illustrates aperture layer 486 as being locatedon the bottom surface (i.e., surface facing optics unit 429) of opticsunit 410, examples of the disclosure can include aperture layer 486located on the top surface of optics unit 410. In some examples,aperture layer 486 can be located on the same layer as optics unit 429,as illustrated in FIG. 4E. Examples of the disclosure can also includeaperture layer 486 located on two layers: the same layer as optics unit410 and the same layer as optics unit 429, as illustrated in FIG. 4F. Insome examples, the aperture layer can comprise an opaque element, suchas a metal, at least in part. In some examples, the aperture layer canbe a lithographically patterned layer applied to one or more surfaces ofthe optics unit(s).

FIG. 4G illustrates one or more optics integrated into the structure ofsystem 400. The integrated optics can be configured to selectivelytransmit light through the optics based on one or more properties, suchas path length or angle of incidence of incident light. In someexamples, system 400 can include one or more integrated optics includedin the optics unit 429, as illustrated in FIG. 4H. In some examples, theintegrated optics illustrated in FIGS. 4G-4H can be continuous with thesurface of optics unit 410 and optics unit 429.

Although FIGS. 4D-4H illustrate optic 416 located on the same layer(e.g., integrated with) as optics unit 429, examples of the disclosurecan include optic 416 located on the same layer (e.g., integrated with)as optics unit 410. Additionally, although FIGS. 4D-4F illustrateaperture layer 486 located on either the bottom side of optics unit 410or the top side of optics unit 429, examples of the disclosure caninclude the same or an additional aperture layer located on the otherside.

FIG. 4I illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple angles of incidence on a samplesurface and reducing or eliminating TIR trapped light from the lightsources according to examples of the disclosure. System 400 can beconfigured such that outcoupler 409 is in contact with the bottomsurface (i.e., the flat surface) of optics unit 429. System 400 can alsobe configured such that detector array 430 is located below (i.e.,opposite optics unit 429) substrate 442. By placing the top surface(i.e., surface where light exits outcouplers 409) of outcouplers 409 incontact with the bottom surface of optics unit 429 and locating detectorarray 430 below the (i.e., away from the direction of light exiting theoutcouplers 409) substrate 442, detector array 430 can be prevented fromerroneously detecting TIR trapped light that has directly exitedoutcouplers 409. Furthermore, locating detector array 430 belowsubstrate 442 can prevent light reflected off the bottom surface (i.e.,the flat surface) of optics unit 429 from being detected by detectorarray 430 and erroneously changing the measured signal.

FIG. 5 illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple angles of incidence on a samplesurface with one-layer of optics according to examples of thedisclosure. System 500 can include one or more components as discussedin the context of and illustrated in FIGS. 4A-4I. Additionally, system500 can include optics unit 512, which can be capable of combining thefunctionality of optics unit 410 and optics unit 429 illustrated inFIGS. 4A-4I. Optics unit 512 can include one or more optics,micro-optics, microlens, or a combination of optics configured tocollect incident light, condition the beam size and shape, and focusincident light. Optics unit 512 can collect light 554 and light 555incident on system 500 with the angles of incidence θ₁ and θ₃,respectively. The optics included in optics unit 512 can change theangle (i.e., redirect the light beam) of light (e.g., light 554 andlight 555) such that light is directed towards detector array 530.Turning light 554 and light 555 can lead to an angle of incidence ondetector array 530 that is less than angles of incidence θ₁ and θ₃,respectively. In some examples, the medium between optics unit 512 anddetector array 530 can be configured with a refractive index such thatthe changes in angle (i.e., bending) of light 554 and light 555increase. In some examples, the medium can be multi-functional and caninclude a conformal insulating material that provides mechanicalsupport. In some examples, the optics included in optics unit 510 canpreferentially collect light rays, included in light 554 and light raysincluded in light 555 with angles of incidence within a range ofcollection angles. In some examples, the range of collection angles forthe optics coupled to light 554 can be different from the range ofcollection angles coupled to light 555.

Additionally, optic 518 and optics 519, included in optics unit 512, canfocus light 554 and light 555 towards detector pixel 533 and detectorpixel 537, respectively, included in detector array 530. Although asystem (e.g., system 400 illustrated in FIGS. 4A-4I) with two-layers ofoptics can include an optics unit (e.g., optics unit 410) that can beconfigured for light collection, turning the beam, and focusing incidentlight, optics unit 512 can be configured with a higher focusing power(i.e., degree which the optics converges or diverges incident light)than the system with the two-layers of optics. In some examples, opticsunit 512 can include a plurality of silicon lenses or lenses includingsilicon dioxide. In some examples, at least two optics included inoptics unit 512 can have different geometric properties. A detaileddiscussion of the properties of the optics in the optics unit 512 isprovided below.

System 500 can also include an aperture layer 586. Aperture layer 586can include a plurality of openings configured to allow light 554 and555 (e.g., any light with an angle of incidence within a range ofcollection angles), respectively, to transmit through. In some examples,aperture layer 586 can be located on an external surface (e.g., thehousing) of system 500 and can be configured to allow light to enterinto system 500. Although FIG. 5 illustrates aperture layer 586 locatedon an external surface of the system 500, examples of the disclosure caninclude aperture layer 586 located on another side (e.g., an internalsurface of the system 500) or another layer.

Each optics included in optics unit 512 can be coupled to a detectorpixel (e.g., detector pixel 533 or detector pixel 537), included indetector array 530. Each optics-detector pixel pair can be associatedwith an optical path in sample 520. In some examples, the associationcan be one optics-detector pixel pair to one optical path. For example,optic 517 and detector pixel 533 can form an optics-detector pixel pairthat is associated with the optical path from light 554, and optic 518and detector pixel 537 can form another optics-detector pixel pair thatis associated with the optical path from light 555. Although FIG. 5illustrates detector pixel 533 and detector pixel 537 as single detectorpixels, each individually associated with optics, examples of thedisclosure can include multiple detector pixels associated with the sameoptics and multiple optics associated with the same detector pixel.

In some examples, the system can be configured with one-layer of opticsto reduce the stackup or height of the system. In some examples, thesystem can be configured with two-layers of optics for higher angularresolution, larger angular range of incident light, or both. In someexamples, the system can be configured with the number of layers ofoptics being different for light emitted from the light sources than forlight collected from the sample. For example, the system can beconfigured with one-layer of optics for light emitted from the lightsources and two-layers of optics for light reflected from the sample, orthe system can be configured with two-layers of optics for light emittedfrom the light sources and one-layer of optics for light reflected fromthe sample.

FIG. 6 illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple optical path lengths withtwo-layers of optics according to examples of the disclosure. System 600can be close to, touching, resting on, or attached to sample 620. Sample620 can include one or more locations, such as location 657 and location659. System 600 can be configured to reimage and/or resolve the opticalpaths in sample 620. For example, system 600 can be configured toreimage the path lengths of the optical paths to another plane (e.g., aplane located closer to detector array 630). Reimaging of the opticalpaths can be performed using one or more layers of optics. System 600can include two layers of optics and a detector array 630 located below(i.e., opposite the surface of sample 620) with the multiple layerssupported by support 614, for example. Located between the two layers ofoptics can be air, a vacuum, or any medium with a refractive index thatcontrasts from the refractive index of the optics.

System 600 can include light sources 602. Light sources can beconfigured to emit light 650. Light source 602 can be any source capableof generating light including, but not limited to, a lamp, laser, LED,OLED, EL source, super-luminescent diode, super-continuum source,fiber-based source, or a combination of one or more of these sources. Insome examples, light sources 602 can be capable of emitting a singlewavelength of light. In some examples, light sources 602 can be capableof emitting a plurality of wavelengths of light. In some examples, lightsources 602 can be tunable sources capable of generating a SWIRsignature. In some examples, at least one of light sources 602 caninclude a III-V material, such as InP or GaSb.

Light from light sources 602 can be combined and amplified usingintegrated tuning elements 604, optical traces (not shown), and amultiplexer (not shown). In some examples, integrated tuning elements604, optical traces, and multiplexer can be disposed on a substrate orincluded in a single optical platform, such as a silicon photonics chip.System 600 can also include a thermal management unit 601 forcontrolling, heating, or cooling the temperature of light sources 602.Coupled to the multiplexer can be outcouplers 609. Outcoupler 609 can beconfigured to focus and/or condition (e.g., shape) light 650 from themultiplexer towards optic 616. In some examples, outcouplers 609 can beconfigured as a single mode waveguide that directs a well-defined (i.e.,directional and sharp) light beam towards optic 616. In some examples,light 650 from outcouplers 609 can be a light beam with any suitableshape (e.g., conical, cylindrical, etc.). Optic 616 can collect light650 and collimate and/or tilt the light beam towards one or morelocations in sample 620. In some examples, optic 616 can include abottom surface (i.e., surface facing outcouplers 609) that is flat and atop surface (i.e., surface facing away from outcouplers 609) that isconvex. One skilled in the art would appreciate that a flat surface caninclude tolerances that result in a 15% deviation. Light that is emittedfrom light sources 602 that is collimated by outcouplers 609, transmitsthrough optic 616, and then exits system 600 can be referred to as light652.

Light 652 can be directed at sample 620 and can be incident on location657. A portion of light 652, referred to as light 654, can reflect backtowards system 600. Additionally, a portion of light 652 can be incidenton location 659 and can reflect back towards system 600, and can bereferred to as light 655. Although light 652 exiting system 600 can be acollimated light beam, scattering events can occur along the light pathdirected to location 657 and location 659, which can lead to light 654and light 655 becoming scattered beams. Both light 654 and light 655 canenter system 600, and can be incident on optic 618 and optic 619,included in optics unit 610, respectively. Optics unit 610 can includeone or more optics, micro/or focus incident light. For example, optic618 can collect light 654, and optic 619 can collect light 655. Optic618 can change the angle (i.e., redirect the light beam) of light 654such that light 654 is directed towards (i.e., closer to normalincidence than the angle of incidence) optic 623 included in optics unit629. In some examples, the medium between optics unit 610 and opticsunit 629 can be configured with a refractive index such that the changein angle (i.e., bending) of light 654 increases. In some examples, themedium can be multi-functional and can include a conformal insulatingmaterial that provides mechanical support. Similarly, optic 619 canchange the angle of light 655 such that light 655 is directed towardsoptic 627 included in optics unit 629. In some examples, optic 618,optic 619, or both can be configured to focus incident light (e.g.,light 654 and light 655). In some examples, optics unit 610 canpreferentially collect light rays included in light 654, light 655, orboth with an angle of incidence within a range of collection angles. Insome examples, optics unit 610 can include a plurality of silicon lensesor lenses including silicon dioxide. Although FIG. 6 illustrates opticsunit 610 attached to support 614, examples of the disclosure can includeoptics unit 610 attached to or coupled to optics unit 629 throughmechanical features etched into optics unit 610, optics unit 629, orboth. In some examples, at least two optics included in optics unit 610can have different geometric properties. A detailed discussion of theproperties of the optics in optics unit 610 is provided below.

System 600 can include an aperture layer 686. Aperture layer 686 caninclude an opening 687 and opening 689 configured to allow light 654 andlight 655 (e.g., any light with an angle of incidence within the rangeof collection angles), respectively, to transmit through. Light 654 thathas been transmitted through opening 687 can be directed towards optic623 included in optics unit 629. Similarly, light 655 that has beentransmitted through opening 689 can be directed towards optic 627included in optics unit 629. Optics unit 629 can comprise a plurality ofoptics, such as optic 623 and optic 627, attached to a substrate. Insome examples, optic 623 and optic 627 can be any type of optics and caninclude any type of material conventionally used in optics. In someexamples, two or more of the optics in optics unit 629 can have the sameoptical and/or geometric properties. One skilled in the art wouldappreciate that the same optical properties and geometric properties caninclude tolerances that result in a 15% deviation.

Light 645 can undergo some refraction from optic 618. Optic 623 canrecollimate light 654 and/or focus light 654 onto detector pixel 633included in detector array 630. Similarly, optic 627 can recollimatelight 655 and/or focus light 655 onto detector pixel 637 included indetector array 630. In some examples, system 600 can be configured suchthat light 654 is redirected by optics unit 610 and focused by opticsunit 629. In some examples, system 600 can be configured such that light654 is redirected by both optics unit 610 and optics unit 629. In someexamples, optics unit 629 can include a plurality of silicon lenses orlenses including silicon dioxide. Although FIG. 6 illustrates opticsunit 629 attached to support 614, examples of the disclosure can includeoptics unit 629 attached to or coupled to optics unit 610 throughmechanical features etched into optics unit 610, optics unit 629, orboth. In some examples, at least two optics included in optics unit 629can have different geometric properties. A detailed discussion of theproperties of the optics in optics unit 629 is provided below.

Light 654 can be transmitted through optic 623 and can be detected bydetector pixel 633 included in detector array 630. Detector array 630can include one or more detector pixels, such as detector pixel 633 anddetector pixel 637 disposed on a substrate. In some examples, thesubstrate can be a silicon substrate. In some examples, at least onedetector pixel can be independently controlled from other detectorpixels in detector array 630. In some examples, at least one detectorpixel can be capable of detecting light in the SWIR range. In someexamples, at least one detector pixel can be a SWIR detector capable ofoperating between 1.5-2.5 μm. In some examples, at least one detectorpixel can be a HgCdTe, InSb, or InGaAs based detector. In some examples,at least one detector pixel can be capable of detecting a positionand/or angle of incidence.

Additionally, light 655 can be transmitted through optic 627 and can bedetected by detector pixel 637. Detector pixel 633 and detector pixel637 can be coupled to an integrated circuit, such as ROIC 641. In someexamples, detector pixel 633 and detector pixel 637 can be coupled tothe same circuitry. In some examples, detector pixel 633 and detectorpixel 637 can be coupled to different circuitry. Each circuit in ROIC641 can store charge corresponding to the detected light (or photons oflight) on the corresponding detector pixel in an integrating capacitorto be sampled and read out by a processor or controller. The storedcharge can correspond to one or more optical properties (e.g.,absorbance, transmittance, and reflectance) of the detected light.

System 600 can include a plurality of optics (e.g., optic 618 and optic619) included in optics unit 610 and a plurality of optics (e.g., optic623 and optic 627) included in optics unit 629, where each of the opticscan be coupled to a detector pixel (e.g., detector pixel 633 or detectorpixel 637) included in detector array 630. Each first optics/secondoptics/detector pixel trio can be associated with an optical path in thesample. In some examples, the association can be one first optics/secondoptics/detector pixel trio to one optical path. For example, optic 618,optic 623, and detector pixel 633 can be associated with the opticalpath from light 654. Optic 619, optic 627, and detector pixel 637 can beassociated with the optical path from light 655. In this manner, system600 can be capable of reimaging and resolving the multiple optical pathswith different path lengths in sample 620, where each detector pixel indetector array 630 can be associated with a different optical path.Although FIG. 6 illustrates detector pixel 633 and detector pixel 637 assingle detector pixels, each individually associated with optics,examples of the disclosure can include multiple detector pixelsassociated with the same optics and multiple optics associated with thesame detector pixel.

As illustrated in the figure, system 600 can be configured such that atleast two first optics/second optics/detector pixel trios can resolvedifferent path lengths. For example, light 654 can have a first opticalpath length, and light 655 can have a second optical path length. Thefirst optical path length associated with light 654 can be differentfrom the second optical path length associated with light 655 due to thedifferent depths of the different locations (e.g., location 657 andlocation 659) that the light rays reflect off. In some examples, light654 can have the same angle of incidence as light 655, but can have adifferent path length. One skilled in the art would appreciate that thesame angle of incidence can include tolerances that result in a 15%deviation. System 600 can couple different detector pixels in detectorarray 630 with different path lengths. For example, detector pixel 633can be associated with the first optical path length, and detector pixel637 can be associated with the second optical path length. In someexamples, the optical system can operate at finite conjugate (i.e., afinite distance where the light rays collimate), and the properties(e.g., focal length, working distance, aperture, pitch, fill-factor,tilt, and orientation) of the optics included in optics unit 610 can bedetermined based on the range of collection angles. In some examples, atleast two optics included in optics unit 610 can have the same geometricproperties, but can be located in different areas of optics unit 610. Adetailed discussion of the properties of the optics in optics unit 610is provided below.

In some examples, the shapes, sizes, and geometric properties of theoptics included in optics unit 610 can be different for an opticalsystem (e.g., system 400 illustrated in FIGS. 4A-4I or system 500illustrate in FIG. 5) configured to resolve different angles ofincidence than an optical system (e.g., system 600 illustrated in FIG.6) configured to resolve different path lengths.

In some examples, each first optics/second optics/detector pixel triocan be associated with a range of collection angles. As illustrated inthe figure, light 654 can scatter from location 657 with a shape thatresembles a cone, for example. System 600 can integrate the angles ofthe light rays included in light 654 azimuthally. Since the path lengthsof the light rays can be the same, the integration of the angles withinthe range of collection angles can reduce the number of angle bins,number of detector pixels, and the complexity of the optics needed forthe optical system. One skilled in the art would appreciate that thesame path length can include tolerances that result in a 15% deviation.For example, an optical system that does not integrate the angles canrequire a minimum of eight detector pixels, whereas an optical systemthat does integrate the angles can require fewer number of detectorpixels.

In addition to needing a smaller number of detector pixels, system 600can utilize a smaller format (i.e., less than a hundred pixels) detectorarray that can have better performance (e.g., optical efficiency,fill-factor, and/or reliability) than a large format detector array.Additionally, by integrating the angles of the light rays, system 600inherently performs spatial averaging of nominally equivalent opticalpaths incident on a detector pixel. The spatial averaging of nominallyequivalent optical paths can lead to more light being incident on adetector pixel, which can lead to a higher signal-to-noise ratio (SNR).Spatial averaging also can lead to better measurement accuracy becauseunimportant light rays can be “canceled” or averaged out.

Although aperture layer 686 is illustrated in FIG. 6 as located betweenoptics unit 610 and optics unit 629, examples of the disclosure caninclude aperture layer 686 located on the same layer as one or moreoptics or components in the system. Similar to the examples illustratedin FIGS. 4D-4I, system 600 can be configured with aperture layer 686located on a surface of optics unit 610. In some examples, aperturelayer 686 can be located on the same layer (e.g., a surface) as opticsunit 629. In some examples, aperture layer 686 can be located on thesame layers as optics unit 610 and the same layer as optics unit 629. Insome examples, system 600 can include one or more recessed optics inoptics unit 610. The recessed optics can be configured to selectivelytransmit light through the optics based on one or more properties, suchas path length and/or angle of incidence of incident light. In someexamples, system 600 can include one or more recessed optics in opticsunit 629. One or more of the recessed optics can be continuous with thesurface of optics unit 610 and optics unit 629. In some examples, system600 can include one or more etched or drilled holes for selectivelytransmitting light through the two-layers of optics to detector array630. With one or more etched or drilled holes used as an aperture layer,system 600 can include one or more spacers located between the surfacesof the two-layers of optics. The one or more spacers can be used tomechanically support the optics.

FIG. 7 illustrates a cross-sectional view of a portion of an exemplarysystem configured for resolving multiple optical path lengths withone-layer of optics according to examples of the disclosure. System 700can include one or more components as discussed in the context of andillustrated in FIG. 6. Additionally, system 700 can include an opticsunit 712 that can be capable of combining the functionality of opticsunit 610 and optics unit 629 illustrated in FIG. 6. Optics unit 712 caninclude one or more optics, micro-optics, microlens, or a combinationconfigured to collect incident light, condition the light beam size andshape, and focus incident light. Optic 718, included in optics unit 712,can collect light 754 reflected off location 757. Optic 719, included inoptics unit 712, can collect light 755 reflected off location 759. Theoptics (e.g., optic 718 and optic 719) included in optics unit 712 canchange the angle (i.e., redirect the light beam) of light (e.g., light754 and light 755) such that light is directed towards detector array730. In some examples, the angles of incidence of light 754 and light755 can be the same, and optic 718 and optic 719 can be configured toredirect incident light by the same degree. One skilled in the art wouldappreciate that the same angles of incidence and same degree can includetolerances that result in a 15% deviation. In some examples, the mediumbetween optics unit 712 and detector array 730 can be configured with arefractive index such that the change in angle (i.e., bending) of light754 and light 755 increases. In some examples, the medium can bemulti-functional and can include a conformal insulating material thatprovides mechanical support. In some examples, the optics unit 712 canpreferentially collect light rays included in light 754 and light raysincluded in light 755 with angles of incidence within a range ofcollection angles.

Additionally, optic 718 and optic 719, included in optics unit 712, canfocus light 754 and light 755 towards detector pixel 733 and detectorpixel 737, respectively, included in detector array 730. Although asystem (e.g., system 600 illustrated in FIG. 6) with two-layers ofoptics can include an optics unit (e.g., optics unit 610) that can beconfigured for light collection, turning the beam, and focusing incidentlight, optics unit 712 can be configured with a higher focusing power(i.e., degree which an optics converges or diverges incident light) thanthe system with the two-layers of optics. In some examples, optics unit712 can include a plurality of silicon optics.

System 700 can also include an aperture layer 786. Aperture layer 786can include a plurality of openings configured to allow light 754 and755 (e.g., any light with an angle of incidence within a range ofcollection angles), respectively, to transmit through. In some examples,aperture layer 786 can be located on an external surface (e.g., thehousing) of system 700 and can be configured to allow light to enterinto system 700. Although FIG. 7 illustrates aperture layer 786 locatedon an external surface of the system 700, examples of the disclosure caninclude aperture layer 786 located on another side (e.g., an internalsurface of the system 700) or another layer.

Each optics included in optics unit 712 can be coupled to a detectorpixel (e.g., detector pixel 733 or detector pixel 737), included indetector array 730. Each optics-detector pixel pair can be associatedwith an optical path in sample 720. In some examples, the associationcan be one optics-detector pixel pair to one optical path. For example,optic 718 and detector pixel 733 can form an optics-detector pixel pairthat is associated with light 754 (or light with the same optical pathlength as light 754), and optic 719 and detector pixel 737 can formanother optics-detector pixel pair that is associated with light 755 (orlight with the same optical path length as light 755). One skilled inthe art would appreciate that the same optical path length can includetolerances that result in a 15% deviation. Although FIG. 7 illustratesdetector pixel 733 and detector pixel 737 as single detector pixels,each individually associated with optics, examples of the disclosure caninclude multiple detector pixels associated with the same optics andmultiple optics associated with the same detector pixel.

In some examples, the system can be configured with one-layer of opticsto reduce the stackup or height of the system. In some examples, thesystem can be configured with two-layers of optics for higher angularresolution, larger angular range of incident light, or both. In someexamples, the system can be configured with the number of layers ofoptics being different for light emitted from the light sources and forlight collected from the sample. For example, the system can beconfigured with one-layer of optics for light emitted from the lightsources and two-layers of optics for light collected from the sample, orthe system can be configured with two-layers of optics for light emittedfrom the light sources and one-layer of optics for light collected fromthe sample.

Although FIGS. 2-7 illustrate the system close to the sample, examplesof the disclosure can include a system configured for touching a surfaceof the sample. In some examples, a surface of the optics unit (e.g.,optics unit 410, optics unit 512, optics unit 610, or optics unit 712)can be touching a surface of the sample. Generally, closer proximity ofthe sample to the optics unit can lead to fewer and smaller opticalcomponents needed in the system, better measurement accuracy, and lowerpower consumption of the system.

The close proximity of the device can exploit a reduced effectivenumerical aperture (NA) of the light rays exiting the sample. Thereduced effective NA can be used to characterize the range of anglesthat the system can accept as reflected light from the sample. Thisreduced effective NA can be due to angles of incidence on the optics anddetector that are closer to normal incidence due to Snell's Law. Withangles of incidence closer to normal, the aperture size and the pitch ofthe optics can be made smaller, leading to a smaller system.Additionally, the detector can receive a higher optical power, which canlead to better measurement accuracy and a system that can be configuredfor lower power consumption.

FIG. 8 illustrates Snell's Law according to examples of the disclosure.Snell's law can describe the properties of a light ray that refracts atan interface between two materials with different refractive indices.Snell's law is stated as:

n₁ sin θ₁=n₂ sin θ₂   (1)

Material 810 can have a refractive n₁, and material 812 can have arefractive index n₂, where the refractive index n₁ can be different fromthe refractive index n₂. The light ray can be incident on the material810-material 812 interface at angle of incidence θ₁. Due to therefractive index difference between the two materials, the light ray canrefract and can enter material 812 at an angle of refraction θ₂different from the angle of incidence θ₁. If material 810 has arefractive index less than the refractive index of material 812, thenthe angle of refraction θ₂ can be reduced (i.e., closer to normalincidence).

With a high enough optical power, the optics unit can act like animmersion lens objective. An immersion lens objective can be a systemwhere the optics and sample are surrounded or immersed in a medium witha contrasting refractive index. A contrasting refractive index can leadto a larger change in reduced effective NA than a non-immersed (e.g.,the optics and sample are surrounded by air) system. A larger change inreduced effective NA can lead to more light refraction, which can reducethe optical aberrations and can lead to better measurement accuracy. Theoptical immersion can also eliminate or reduce TIR at the exteriorinterface of the system (e.g., interface where the system contacts thesample), which can lead to more light reaching the detector. As a resultof more light reaching the detector, the light sources included in thesystem can be driven with less power, and thus, the system can requireless power.

Additionally, the close proximity of the optics unit to the sample canallow the system to employ a well-defined (i.e., definite and distinct)interface, such as the exterior interface of the system (e.g., interfacewhere the system contacts the sample), as a reference. The system mayneed to accurately reference the “beginning” or “edge” of the sample inorder to reimage and resolve the multiple optical paths within thesample. With the exterior interface of the system (e.g., interface wherethe system contacts the sample) as a reference, fewer optical elementsor components (e.g., a separate window) may be needed, since otherwisean additional optical component can be required to create thewell-defined interface. Fewer optical components can lead to a morecompact system.

In addition to locating the device in close proximity (e.g., touching)to the sample, the measurement region of the sample can affect thesystem's capability of accurately reimaging and resolving multipleoptical paths within the sample. One factor that can affect the accuratereimaging and resolution can be the measurement path length. Themeasurement path length can be selected based on a targeted (e.g.,pre-determined) path length, which can be a path length such that thespectroscopic signal measured by the detector accurately represents thedesired one or more properties of the sample. The targeted measurementpath length can be determined based on the scale lengths of the sample.The scale lengths of the sample can be based on the mean absorptionlength in the sample and the reduced scattering length in the sample.

The mean absorption length in a sample can be the distance over whichlight can attenuate. If the measurement path length is longer than themean absorption length, the remaining signal (i.e., signal that has notscattered) or the measured signal intensity can be reduced, while anynoise sources may not attenuate by an equivalent amount. As a result ofthe imbalance in attenuation, the SNR can be lower. The mean absorptionlength can be defined by the Beer-Lambert Law, which can mathematicallydescribe the absorption A of light by a substance in a sample at a givenwavelength as:

A=ecL   (2)

where e is the molar absorptivity (which can vary with wavelength), L isthe path length through the sample that light has to travel, and c isthe concentration of the substance of interest.

If the background absorption (i.e., absorption by substances differentfrom the substance of interest) is high, the path length through thesample that light has to travel can be less than the mean absorptionlength. If the background absorption is negligible, the path length canbe the same as the mean absorption length. One skilled in the art wouldappreciate that the same path length can include tolerances that resultin 15% deviation. In some examples, the mean absorption length can beselected such that the mean absorption length is greater than or equalto the path length through the sample that light has to travel.

The reduced scattering length can be the distance over which informationabout the optical path is lost (i.e., randomized or decorrelated). Thereduced scattering length can be determined by:

μ_(s)′=μ_(s)(1−g)   (3)

where 1/μ_(s) is the mean free path between scattering events and g isthe scattering anisotropy. If the measurement path length is greaterthan the reduced scattering length, the measurement accuracy can becompromised. In some examples, the measurement path length can beselected such that the measurement path length is less than the reducedscattering length.

In some examples, the mean absorption length can be different from thereduced scatter length, and the measurement path length can be selectedbased on the smaller of the mean absorption length and reducedscattering length. In some examples, the mean absorption length can beshort or absorption of light in the sample can be strong such that thesignal of reflected light is undetected, and the system can beconfigured to increase the optical power of the light sources orincrease the sensitivity of the detector to compensate. In someexamples, the amount of compensation can be based on the powerconsumption, optical damage to the sample, unwanted heating effects inthe sample, effects to the photon shot-noise, detected stray light thathas not transmitted through the sample, or any combination of effects.Therefore, the selection of the measurement path length can affect notonly the measurement accuracy, but also the power consumption,reliability, and lifetime of the system.

Additionally or alternatively, the system can be configured to utilizethe effective scale length when the optical parameters of the samplevary (e.g., by more than 10%) with wavelength, for example. Theeffective scale length can be determined by calculating individual scalelength for each wavelength, and taking an average of the individualscale lengths across the wavelengths of interest. In some examples, theindividual scale length for each wavelength can be calculated todetermine the range of individual scale lengths. The system can beconfigured to select the minimum scale length (among the range ofindividual scale lengths), the maximum scale length (among the range ofindividual scale lengths), or any scale length between the minimum scalelength and the maximum scale length. In some examples, the measurementpath length can be selected based on the mean absorption length, reducedscattering length, minimum scale length, maximum scale length, or anycombination.

As discussed above, the scale length can be used to determine the sizeof the measurement region on the sample. Light outside of themeasurement region can be light rays that have undergone multiple randomscattering events within the sample, and as a result, these light rayscan be decorrelated from the optical path traveled within the sample.Decorrelated light rays may not contribute useful information for anaccurate measurement, and as a result, can be discarded or ignoredwithout sacrificing an accurate measurement.

For example, the wavelengths of interest can be between 1500 nm-2500 nm(i.e., SWIR range), and the mean absorption length and reducedscattering length averaged over the wavelengths of interest can be 1 mm,which can correspond to a scale length of 1 mm. This scale length cancorrespond to a region of the sample with a diameter of 1-2 mm to beused for collecting light exiting the sample. That is, the majority(e.g., greater than 70%) of the optical power that exits the sample canbe concentrated within this 1-2 mm diameter region, and the light raysexiting the sample outside of this region can be ignored.

The scale length can be also used to determine the size of the inputlight beam emitted from the outcoupler. The size of the light beam canaffect the optical power (i.e., optical intensity) and diffractioneffects. Measurement accuracy can favor a collimated input light beam inorder for the system to operate with a sufficient optical power (e.g., asignal with a high enough SNR that can be detected by the detector) andminimal diffraction effects. For example, a scale length of 1 mm cancorrespond to a collimated input light beam with a beam diameter between100-300 μm. In some examples, the input light beam can be configuredwith a beam diameter of less than 175 μm.

Similar to the properties of the input light beam, the properties of theoptics unit(s) can also affect the system. The optics unit(s) can beformed on a single substrate or layer or can be formed on two or moresubstrates or layers. In some examples, the optics unit(s), detectorarray, light sources, or any combination can be mounted onto the sameoptical platform. In some examples, the optics unit(s) can have a plano(i.e., flat) surface contacting the sample. Configuring the optics witha plano surface can reduce wafer handling and fabrication complexity. Insome examples, the other surface (i.e., the surface opposite the sample)can be convex to enhance the optics power. In some examples, this othersurface can be a single convex refracting surface. In some examples, thethickness of the optics unit(s) can be based on the amount of lightbending. In some examples, the thickness can be between 100-300 μm.

FIGS. 9A-9B illustrate top and perspective views of an exemplary opticsunit according to examples of the disclosure. A group 900 can include aplurality of units, each unit including at least three regions: launchregion 916, reference region 922, and measurement region 929.

Launch region 916 can be configured to prevent any specular reflectionfrom reaching the detector array. Launch region 916 can include a lightblocker or light absorber capable of blocking or absorbing light. Insome examples, the light blocker can include any material that preventsincident light from reflecting (e.g., an anti-reflection coating). Insome examples, the light blocker can include any material that reflectsat wavelengths different from the detection wavelengths of the detectorarray. In some examples, launch region can include an opaque mask.

Reference region 922 can include any type of optics (e.g., a negativemicrolens) configured for spreading out incident light beams. Lightemitted from the light source can be directed at a reference (e.g.,reference 222 included in system 200), which can relay light toreference region 922. Reference region 922 can spread out that lightsuch that one or more light beams are directed to detector pixels on thedetector array. In some examples, reference region 922 can include anegative lens or a lens with a focal length that is negative. In someexamples, reference region 922 can include a prism. In some examples,reference region 922 can include a different prism wedge angled for eachdetector pixel in the detector array. In some examples, reference region922 can include a beamsplitter. In some examples, reference region 922can be configured to spread out or divide light into multiple beams. Insome examples, reference region 922 can be configured to uniformlyspread out light such that one or more properties of each light beam isthe same. One skilled in the art would appreciate that the sameproperties can include tolerances that result in a 15% deviation. Insome examples, reference region 922 can be configured to spread out thelight beam such that intensities of at least two light beams aredifferent. In some examples, reference region 922 can include multipleoptics. In some examples, the size and/or shape of optics included inreference region 922 can be based on the number of detector pixelsand/or the properties of the one or more light beams exiting referenceregion 922. In some examples, one or more aperture layers can be locatedin reference region 922 to control the properties and/or direction oflight exiting reference region 922.

Measurement region 929 can include one or more collection optics (e.g.,a positive microlens). The collection optics can be configured toreimage and resolve multiple optical paths in the sample, as discussedabove. The system can be configured to chop or alternate betweenemitting light from the light source to be incident on reference region922 and emitting light from the light source to be incident onmeasurement region 929. The properties of the collection optics will bediscussed below.

Although FIGS. 4A-7 illustrate units included the system, where eachunit can include one light beam from the outcoupler that exits thesample and is collected by a conjugate optic system and detector array,examples of the disclosure include systems with multiple units. FIG. 9Cillustrates a top view of an exemplary optics unit and detector arrayincluded in multiple groups included in a system according to examplesof the disclosure. The system can include a plurality of groups 900coupled to a detector array 930. In some examples, one or more opticsincluded in measurement region 929 can be “shared” between adjacentgroups 900. In some examples, the system can be configured with one ormore groups with light sources that alternate emitting light to theshared optics. In some examples, the system can be configured with 27groups 900 and a 9×3-detector array 930. In some examples, each group900 can be separated from another group 900 by at least 2 mm. AlthoughFIGS. 9A-9B illustrate groups 900 arranged with the reference region 922located between the launch region 916 and a grid of 3×3 optics includedin the measurement region 929, examples of the disclosure can includeany arrangement of the three regions and any arrangement of the opticsincluded in the measurement region 929. For example, the launch region916 can be located in the center of group 900, and the optics cansurround the outer edges of the launch region 916.

As discussed above, the configuration and properties of the opticsincluded in the optics unit(s) can be based on numerous factors. Theseproperties can include the effective focal length, working distance,material of the optics, the fill-factor, the aperture size, the pitch,the tilt (or decenter), and the orientation (or rotation), as will bediscussed.

The system can be configured with an effective focal length based on therelationship between the range of collection angles and the location onthe surface of the detector (or detector pixel) that the light ray isincident upon. The system can also be configured based on theintegration of the detector array.

Since the optics unit(s) is located in the path between the sample andthe detector, the material of the optics can affect the opticalproperties of the detected light, and thus, the measurement accuracy. Toallow light exiting the sample to reach the detector array, the opticscan be configured with a material that is transparent over thewavelength range of interest such that light can be prevented fromreflecting off the surfaces of the optics. Additionally, in exampleswhere the optics unit is in contact with the sample, the material of theoptics can be based on resistance to material degradation from chemicaland physical exposure of the optics to the sample. Furthermore, otherconsiderations, such as compatibility with wafer-scale processing forcreating any patterns (e.g., etch profiles) for the optics unit,availability of a material, and cost can be considered.

The material of the optics unit can also be selected based on therefractive index of the sample. For example, the system can beconfigured with an optics unit with a refractive index of 3.4 (e.g., anunit of silicon lenses) (or within 10%) when the sample has a refractiveindex 1.42 (or within 10%). Incident light can have an angle ofincidence of 45° at the exterior interface of the system (e.g.,interface where the system contacts the sample), which can lead to anangle of refraction of 16.9°. In this manner, the material of the opticsunit can be selected such that the angle of incidence on the surface ofthe detector array can be closer to normal, which can be lead to thedetector receiving a higher optical power, better measurement accuracy,and a system that can be configured for lower power consumption.

Furthermore, the material of the optics unit can be selected such thatless “spreading” (i.e., dispersion of the bundles of light between theexterior interface of the system (e.g., interface where the systemcontacts the sample) and the surface of the detector) of light raysoccurs. For example, light incident on the exterior interface of thesystem (e.g., interface where the system contacts the sample) with anangle of incidence of 60° can lead to an angle of refraction of 20.9°.Without a refractive index contrast between the optics unit and thesample, the spreading would be 15° (i.e., 60°-45°), whereas with arefractive index contrast between the optics unit and the sample, thespreading of light rays can be 4° (i.e., 20.9°-16.9°). A smaller spreadof light rays can lead to a narrower range of collection angles, whichcan result in smaller optics and a more compact system.

In some examples, the wavelength range of interest can be SWIR (i.e.,1500 nm-2500 nm), and the optics unit can include single-crystalSilicon, Sapphire, fused Silica, oxide glasses, chalcogenide glasses,gallium arsenide (GaAs), Zinc Selenide (ZnSe), Germanium (Ge), or anycombination of these materials.

The diameters of the optics can be based on the size of the light beamemitted from the light source. For example, a system configured with alight beam diameter between 100-300 μm can also be configured with anoptics unit with diameters between 100-300 μm.

The fill-factor of the optics unit can represent the percentage orfraction of light rays exiting the sample that is collected. In general,reduced spreading of bundles of incident light can lead to a higherfill-factor (i.e., ratio of the area of light directed at the detectorto the total area of the optics) at the optics unit, and hence, can leadto a higher optical efficiency. The fill-factor of an optic can bedetermined by:

$\begin{matrix}{{FF} = {\frac{\pi}{4}\left( \frac{AD}{pitch} \right)^{2}}} & (4)\end{matrix}$

where AD is the aperture size. The fill-factor FF of a lens ormicro-lens can represent the amount of light that exits the sample,refracts into the system, and transmits through an aperture. In someexamples, the aperture size of an aperture associated with an opticsincluded in the optics unit(s) included in the optics unit can be basedon the spread of the incident light rays. With a lower amount ofspreading of incident light rays, the aperture size and optics pitch canbe decreased such that a high fill-factor is achieved without loss ofincident light rays that include pertinent information (e.g.,information that can contribute to better measurement accuracy). In someexamples, the optics unit can be configured with a fill-factor FF of 25%or greater. In some examples, the optics unit can be configured with afill-factor FF of 50% or greater. In some examples, the optics unit canbe configured with a fill-factor FF of 60% or greater.

The pitch of the optics unit can be the distance between adjacentoptics, which can affect the size of the optics. In some examples, thepitch can be based on the fill-factor of the optics unit. As illustratedin Equation 4, the fill-factor of the optics unit can be related to theaperture size, so pitch of the optics unit can be also based on theaperture size. To increase the fill-factor and the efficiency ofcapturing light rays exiting the sample, the pitch can be greater thanthe aperture size. For example, for an aperture size between 100-300 μm,the optics can be configured with a pitch between 125-500 μm. In someexamples, the aperture size can be configured to be 175 μm in diameter,the pitch can be 250 μm, and the fill-factor can be 38.4%.

Additionally or alternatively, the optics pitch and the aperture sizecan be based on the range of collection angles. The aperture size candetermine which among the light rays exiting the sample are accepted(i.e., transmitted through to the detector) by the optics and which arerejected (i.e., prevented from reaching the detector). The samplematerial and substances in the sample can lead to a high anisotropy ofscattering. As a result, the collection efficiency (i.e., efficiency ofthe collected scattered light) can be based on the range of collectionangles. While a wider range of collection angles can lead to more lightcollection (i.e., higher optical power), the collected light may includea larger proportion of unwanted light (e.g., noise or decorrelatedlight). Different angles of collected light rays can have a differentimportance or relevance to an accurate measurement. In some examples,the optical power of the light rays can be lower as light deviates(e.g., greater than 70°) from normal incidence on the detector surface.The light rays with angles of incidence that deviate from normalincidence can include light rays with smaller crossing angles with lightemitted from the light source (which can lead to a larger uncertainty inthe scattering location or path length) and light rays with a largenumber of scattering events. As a result, light rays with angles ofincidence that deviate from normal incidence can be less relevant andcan lead to less accurate measurements. Furthermore, light rays thatdeviate from normal incidence can include light scattered from locationsat shallow depths within the sample. In some applications, substances ofinterest in a sample may be located deep within the sample, so lightrays scattered from locations at shallow depths within the sample maynot contribute relevant information to the measurement.

Affected by the range of collection angles can be the aperture size,optics or optics pitch, collection efficiency, optical power incident onthe detector, and the power of the system. The range of collectionangles that the system can be configured to measure can be based on atargeted (e.g., pre-determined) range of collection angles. The targetedrange of collection angles can be determined based on several factors,such as the collection efficiency, geometrical path uncertainty, numberof scattering events likely to occur within the sample, depth ofpenetration, and limitations of the optics design, which can bedetermined based on the path length of a light ray. To determine thepath length of a light ray, multiple uncertainties that exist can beconsidered. The total path length uncertainty ΔPL can include spatialresolution uncertainty Δspatial, angular resolution uncertaintyΔangular, input Gaussian angular divergence Δinput, and low-angle samplescatter uncertainty Δmultiple_scatter, and can be defined as:

ΔPL ²=(Δspatial)²+(Δangular)²+(Δinput)²+(Δmultiple_scatter)²   (5)

The properties of one or more of the optics and aperture layers in thesystem can be configured based on the spatial resolution uncertainty.FIG. 10 illustrates an exemplary configuration with light rays having aspatial resolution uncertainty according to examples of the disclosure.System 1000 can be touching or in close proximity to sample 1020. Lightcan exit system 1000 at location 1006 and can travel a length d₁₁through sample 1020 to location 1010. The angle of the incidence oflight at location 1010 can be angle of incidence θ₁. A portion of lightcan scatter at a scattering angle θ₄, travel a length d₁₂ through sample1020, and can reach the exterior interface of the system (e.g.,interface where the system contacts the sample) at location 1016. Thedistance between location 1006 and location 1016 can be referred to asdistance x. Another portion of light can travel further into the sample1020, traveling a total length d₂₁, to location 1040. In some examples,the angle of incidence of light at location 1040 can also be the angleof incidence θ₁, and light can also scatter at the scattering angle θ₄.The scattered light can travel a length d₂₂ through sample 1020 and canreach the exterior interface of the system (e.g., interface where thesystem contacts the sample) at location 1046. The spatial resolution orthe distance between location 1016 and location 1046 can be referred toas spatial resolution or distance Δx.

The spatial resolution uncertainty Δspatial can be based on thedifference in optical path lengths between scattered light incident atlocation 1016 and scattered light incident at location 1046 and can bedefined as:

Δspatial=d ₂₁ +d ₂₂ −d ₁₁ −d ₁₂   (6)

Based on the law of sines:

$\begin{matrix}{\frac{x}{\sin \left( {\theta_{1} + \theta_{4}} \right)} = {\frac{d_{12}}{\sin \left( {{90{^\circ}} - \theta_{1}} \right)} = \frac{d_{11}}{\sin \left( {{90{^\circ}} - \theta_{4}} \right)}}} & (7) \\{d_{11} = {\frac{\sin \left( {{90^{\circ}} - \theta_{4}} \right)}{\sin \left( {\theta_{1} + \theta_{4}} \right)}x}} & (8) \\{d_{12} = {\frac{\sin \left( {{90^{\circ}} - \theta_{1}} \right)}{\sin \left( {\theta_{1} + \theta_{4}} \right)}x}} & (9) \\{d_{21} = {\frac{\sin \left( {{90^{\circ}} - \theta_{4}} \right)}{\sin \left( {\theta_{1} + \theta_{4}} \right)}\left( {x + {\Delta x}} \right)}} & (10) \\{d_{22} = {\frac{\sin \left( {{90^{\circ}} - \theta_{1}} \right)}{\sin \left( {\theta_{1} + \theta_{4}} \right)}\left( {x + {\Delta x}} \right)}} & (11)\end{matrix}$

Therefore, the spatial resolution uncertainty Aspatial can be reducedto:

$\begin{matrix}{{\Delta \; {spatial}} = {\frac{{\sin \left( {{90^{\circ}} - \theta_{1}} \right)} + {\sin \left( {{90^{\circ}} - \theta_{4}} \right)}}{\sin \left( {\theta_{1} + \theta_{4}} \right)}\left( {\Delta x} \right)}} & (12)\end{matrix}$

As illustrated in Equation 12, the spatial resolution uncertaintyΔspatial can decrease as the angle of incidence θ₁, and scattering angleθ₄ can increase. Additionally, the spatial resolution uncertaintyΔspatial can increase as the spatial resolution Δx (i.e., distancebetween light incident at location 1016 and light incident at location1046) increases. In some examples, the aperture size, tilt, ororientation of the optics, or a combination can be configured based onthe spatial resolution uncertainty Δspatial. In some examples, thespatial resolution uncertainty Δspatial can be between 150-200 μm, whichcan coincide with an angle of incidence θ₁=45° and collection angle(which can be equal to the scattering angle θ₄) of 45°.

The properties of one or more of the optics in the system can also beconfigured based on the angular resolution uncertainty. FIG. 11illustrates an exemplary configuration with light rays having an angularresolution uncertainty according to examples of the disclosure. System1100 can be touching or in close proximity to sample 1120. Light canexit system 1100 at location 1106, and can travel a length d₁₁ throughsample 1120 to location 1110. The angle of incidence of at location 1110can be angle of incidence θ₁. A portion of light can scatter fromlocation 1110 at a scattering angle θ₅, travel a length d₁₂ throughsample 920, and reach the exterior interface of the system (e.g.,interface where the system contacts the sample) at location 1146. Thechange in refractive index at the exterior interface of the system(e.g., interface where the system contacts the sample) can lead to anangle of refraction θ₈. Another portion of light can travel further intosample 1120, traveling a total length d₂₁, to location 1140. In someexamples, the angle of incidence of light at location 1140 can also beangle of incidence θ₁, and light scattered from location 1140 can have ascattering angle θ₆. In some examples, scattering angle θ₆ can bedifferent from scattering angle θ₁. Light scattered from location 1140can travel a length d₂₂ through sample 1120 and reach the exteriorinterface of the system (e.g., interface where the system contacts thesample) at location 1146. The change in refractive index at the exteriorinterface of the system (e.g., interface where the system contacts thesample) can lead to an angle of refraction θ₇. The distance betweenlocation 1106 and location 1146 can be referred to as distance x. Insome examples, angle of refraction θ₈ can be different from angle ofrefraction θ₇ by an angular resolution of Δθ.

The angular resolution uncertainty Δangular can be based on thedifference in angles of refraction between the two scattered light beams(e.g., light scattered from location 1110 and light scattered fromlocation 1140) and can be defined as:

Δangular=d ₂₁ +d ₂₂ −d ₁₁ −d ₁₂   (13)

Based on the law of sines and Snell's law:

$\begin{matrix}{d_{11} = {\frac{\sin \left( {{90^{\circ}} - \theta_{6}} \right)}{\sin \left( {\theta_{1} + \theta_{6}} \right)}x}} & (14) \\{d_{12} = {\frac{\sin \left( {{90^{\circ}} - \theta_{1}} \right)}{\sin \left( {\theta_{1} + \theta_{6}} \right)}x}} & (15) \\{d_{21} = {\frac{\sin \left( {{90^{\circ}} - \theta_{5}} \right)}{\sin \left( {\theta_{1} + \theta_{5}} \right)}x}} & (16) \\{d_{22} = {\frac{\sin \left( {{90^{\circ}} - \theta_{5}} \right)}{\sin \left( {\theta_{1} + \theta_{5}} \right)}x}} & (17)\end{matrix}$

Therefore, the angular resolution uncertainty Δangular can be reducedto:

$\begin{matrix}{{\Delta \; {angular}} = {\left\lbrack {\left( \frac{\begin{matrix}{{\sin \left( {{90^{o}} - \theta_{6}} \right)} +} \\{\sin \left( {{90^{o}} - \theta_{1}} \right)}\end{matrix}}{\sin \left( {\theta_{6} + \theta_{1}} \right)} \right) - \left( \frac{\begin{matrix}{{\sin \; \left( {{90^{o}} - \theta_{5}} \right)} +} \\{\sin \left( {{90^{o}} - \theta_{1}} \right)}\end{matrix}}{\sin \left( {\theta_{5} + \theta_{1}} \right)} \right)} \right\rbrack x}} & (18)\end{matrix}$

As illustrated in Equation 18, the angular resolution uncertaintyΔangular can increase as the distance x between light emitted from thelight source and the exit location increases. In some examples, thesystem can be configured with a distance between the light source andthe corresponding optics included in the optics unit that is based onthe angular resolution uncertainty Δangular. In some examples, thesystem can be configured with a range of collection angles (i.e., anglebin) based on the angular resolution uncertainty Δangular. In someexamples, the tilt, orientation, or both of the optics in the system canbe configured based on the angular resolution uncertainty Δangular. Insome examples, the angular resolution uncertainty can be between 40-100μm, and the range of collection angles can be between 5° and 10°.

The properties of the light beam in the system can be configured basedon the Gaussian angular divergence. FIG. 12 illustrates an exemplaryconfiguration with an input light beam with a Gaussian angulardivergence according to examples of the disclosure. System 1200 can betouching or in close proximity to sample 1220. Light can exit system1200 at location 1206 and can have an angle of incidence θ₁ (measuredrelative to the half-angle divergence θ₁₂). In some examples, a portionof light emitted from the light sources can diverge with a portion oflight having an angle of incidence θ₁₀ at location 1210 and travel alength d₂₁ through sample 1220 to location 1210. Another portion oflight emitted from the light sources can diverge with an angle ofincidence θ₁₁ also at location 1210 and travel a length d₁₂ throughsample 1220 to location 1210. Light can scatter from location 1210 tolocation 1246 on the exterior interface of the system (e.g., interfacewhere the system contacts the sample) at a scattering angle θ₁₃. Aportion of the scattered light can travel a length d₁₂ through sample1220, and the other portion of the scattered light can travel a lengthd₂₂ through sample 1220. The change in refractive index at the exteriorinterface of the system (e.g., interface where the system contacts thesample) can lead to angle of refraction θ₁₄.

The Gaussian angular divergence Δinput can be based on the difference inoptical path lengths between the diverged light rays and can be definedas:

Δinput=d ₂₁ +d ₂₂ −d ₁₁ −d ₁₂   (19)

Based on the law of sines:

$\begin{matrix}{d_{11} = {\frac{\sin \left( {{90^{\circ}} - \theta_{13}} \right)}{\sin \left( {\theta_{13} + \theta_{1} + \theta_{12}} \right)}x}} & (20) \\{d_{12} = {\frac{\sin \left( {{90^{\circ}} - \theta_{1} - \theta_{12}} \right)}{\sin \left( {\theta_{13} + \theta_{1} + \theta_{12}} \right)}x}} & (21) \\{d_{21} = {\frac{\sin \left( {{90^{\circ}} - \theta_{13}} \right)}{\sin \left( {\theta_{13} + \theta_{1} - \theta_{12}} \right)}x}} & (22) \\{d_{22} = {\frac{\sin \left( {{90^{\circ}} - \theta_{1} + \theta_{12}} \right)}{\sin \left( {\theta_{13} + \theta_{1} - \theta_{12}} \right)}x}} & (23)\end{matrix}$

As the Gaussian angular divergence Δinput increases, the path lengthuncertainty ΔPL can become dominated by the angular resolutionuncertainty Δangular. In some examples, the spatial resolutionuncertainty can contribute to more than half of the path lengthuncertainty ΔPL. In some examples, the system can be configured with arange of collection angles of 50° with 5-10 angle bins.

The tilt of the optics can be configured based on the collectionefficiency, which can affect measurement accuracy and the powerconsumption of the system. By tilting (i.e., orienting the axis) of theoptics such that the collection direction is parallel to the axis ofincident light (i.e., the collection direction faces incident lightdirection), the collection efficiency can be increased. For example, theaxis of incident light can be at 45°, and the collection direction canbe at −45°. In some examples, the tilt of the optics can be based on therange of collection angles. For example, the collection angles can rangefrom 0° to −75°, and the collection direction can be at −37.5°. In someexamples, the collection angles can range from −25° to −70°, and thecollection direction can be at −47.5°. In some examples, the collectionangles can range from −30° to −60°, and the collection direction can beat −45°. In some examples, the optics can include a convex surface,which can be tilted (or decentered) to account for any asymmetry (i.e.,bias) in the range of collection angles. Compensating for any asymmetrycan reduce the magnitude or effects of the optical aberrations of theoptics. In some examples, all the optics can be tiled in the samedirection from normal incidence.

In addition to optics, the system performance can be affected by theproperties of one or more other components included in the system. Insome examples, the system can include a spacer located between theoptics unit and the optical platform. In some examples, the optics unitand optical platform can include single-crystal Silicon. In someexamples, the light sources, optical traces, or both can include siliconwaveguides formed on the optical platform. In some examples, the ROICcoupled to the detector can be fabricated on silicon. By configuring oneor more of the optics unit, optical platform, and ROIC to includesilicon, the thermal expansion of the components can be similar, whichcan minimize any mechanical weaknesses, and the robustness of the systemcan be improved. Additionally, silicon can be a material with manydesirable properties, such as good mechanical strength, good thermalconductance, low cost, and good reliability.

In some examples, the system can include an optical spacer windowlocated between the optics and the sample. FIG. 13A illustrates across-sectional view of an exemplary system including an optical spacerwindow and aperture layer located between the optical spacer window andthe sample according to examples of the disclosure. System 1300 caninclude light sources 1302, optics unit 1312, aperture layer 1386, andoptical spacer window 1321, where optical spacer window 1321 can be incontact with sample 1320. Light sources 1302 can emit light 1352 exitingsample 1320. Light, referred to as light 1354, can reflect off location1357 within sample 1320, can be transmitted through aperture layer 1386,and can reach optics unit 1312.

As illustrated in FIG. 13A, placement of aperture layer 1386 can lead tostray light generated by scattering at the edge interfaces and opticalaberrations, which could degrade the imaging properties of optics unit1312. FIG. 13B illustrates a cross-sectional view of an exemplary systemincluding an optical spacer window and aperture layer located betweenthe optical spacer window and the optics unit according to examples ofthe disclosure. With aperture layer 1387 located between optical spacerwindow 1321 and optics unit 1312, light rays light 1354 can propagate tothe appropriate optics included in optics unit 1312 and stray lightgenerated by scattering at the edge interfaces can be reduced oreliminated.

In some examples, optical spacer window 1321 can be multi-functional andcan be configured to provide mechanical support to the optics. Thethickness of optics unit 1312 can be configured based on the amount oflight bending performed by optics unit 1312 and the ability to separatedifferent angles of refraction. As the thickness of optics unit 1312decreases, the performance of optics unit 1312 increases. However, adecrease in thickness of the optics unit 1312 can lead to an optics unitthat is fragile, costly, and can require complicated fabrication schemeswith low yields. The system can be configured such that the opticalspacer window 1321 compensates for the fragility of a thin optics unit1312 without compromising optical performance. In some examples, thethickness of optical spacer window 1321 can be between 400-700 μm. Insome examples, the thickness of optical spacer window 1321 can be 650μm.

In some examples, optical spacer window 1321 can be configured with athickness such that thermal crossover effects between sample 1320 andthe active components (e.g., detector, light source, and electronics)can be reduced. The active components can generate heat and can also besensitive to any temperature fluctuations, and the temperature of sample1320 can vary or can be different from the operating temperature of theactive components. As a result, a difference in temperature of sample1320 and operating temperature of the active components can lead tothermal crossover effects, which can degrade the measurement accuracy.In some examples, sample 1320 can be skin, for which any difference intemperature can cause discomfort if the thermal crossover effects arenot otherwise mitigated.

In some examples, optical spacer window 1321 can include an intermediatecoating (i.e., a dielectric material with a refractive index between therefractive index of sample 1320 and the refractive index of optics unit1312). Without an intermediate coating, optics unit 1312 or anyanti-reflection coating disposed on optics unit 1312 would be configuredsuch that a high refractive index contrast between optics unit 1312 andsample 1320 would result or the angle of refraction in the system wouldbe compromised. The inclusion of an intermediate coating, on the otherhand, can reduce the complexity and increase the angle of refraction inthe system.

In some examples, optical spacer window 1321 can include a dielectricmaterial. In some examples, the dielectric material can have higherchemical durability, higher physical durability, or both compared to theoptics. In some examples, optical spacer window 1321 can includesapphire. By including an optical spacer window between the optics andthe sample, the system can have enhanced mechanical robustness, enhanceddevice durability, and reduced thermal crossover.

The inclusion of optical spacer window 1321 can alter the manner inwhich light is distributed among the optics and detector pixels in thedetector array. However, this alteration can be accounted for and lightincident on the detector array can still allow each detector pixel todescribe a trajectory or optical path in the sample. FIG. 14Aillustrates a cross-sectional view of an exemplary system excluding anoptical spacer window and corresponding determination of the lateralposition of light incident at the exterior interface of the system(e.g., interface where the system contacts the sample) according toexamples of the disclosure. System 1400 can include light sources 1402,optics unit 1412, aperture layer 1486, and detector array 1430. Lightsources 1402 can emit light 1452 exiting sample 1420 at location 1406.Light 1453, light 1454, and light 1455 can reflect off location 1457within sample 1420 and can be incident on the exterior interface of thesystem (e.g., interface where the system contacts the sample) atlocation 1446, which can be located a distance x away from location1406. Light 1453, light 1454, and light 1455 can transmit throughaperture layer 1486 and can reach optic 1418 included in optics unit1412. Detector array 1430 can include detector pixel 1433, detectorpixel 1435, and detector pixel 1437. Light 1453 can be incident ondetector pixel 1433, light 1454 can be incident on detector pixel 1435,and light 1455 can be incident on detector pixel 1437. Therefore, optic1418, detector pixel 1433, detector pixel 1435, and detector pixel 1437can be associated with location 1446. In this manner, the lateralposition of incident light at the exterior interface of the system(e.g., interface where the system contacts the sample) can be associatedwith the optics included in the optics unit.

Inclusion of the optical spacer window can lead to a determination ofthe lateral position of incident light at the exterior interface of thesystem (e.g., interface where the system contacts the sample) based onboth the optics included in the optics unit and the detector pixelincluded in the detector array. FIG. 14B illustrates a cross-sectionalview of an exemplary system including an optical spacer window andcorresponding determination of the lateral position of light incident atthe exterior interface of the system (e.g., interface where the systemcontacts the sample) according to examples of the disclosure. System1490 can include light sources 1402, optics unit 1412, aperturelayer1487, optical spacer window 1421, and detector array 1430. Lightsources 1402 can emit light 1452 exiting system 1490 at location 1406.Light 1452, light 1451, and light 1453 can reflect off location 1457within sample 1420, can transmit through aperture layer 1487, and cantravel through optical spacer window 1421. In some examples, thescattering angles of light 1452, light 1451, and light 1453 can bedifferent. Sample 1420 can include a plurality of locations, such aslocation 1447, location 1448, and location 1449 at the exteriorinterface of the system (e.g., interface where the system contacts thesample). Location 1447 can be located a distance x₁ away from location1406, location 1448 can be located a distance x₂ away from location1406, and location 1449 can be located a distance x₃ away from location1406. Light 1452 can be incident at location 1447, light 1451 can beincident at location 1448, and light 1453 can be incident at location1449. Detector array 1430 can include detector pixel 1434, detectorpixel 1436, and detector pixel 1438. Light 1452 can be incident ondetector pixel 1434. Similarly, light 1451 and light 1453 can beincident on detector pixel 1436 and detector pixel 1438, respectively.Detector pixel 1434 can be associated with location 1447, detector pixel1436 can be associated with location 1448, and detector pixel 1438 canbe associated with location 1449. Each location (e.g., location 1447,location 1448, and location 1449) can have a different lateral position,which can be associated with a different scattering angle. In thismanner, the lateral position of incident light at the exterior interfaceof the system (e.g., interface where the system contacts the sample) canbe associated with both the optics included in the optics unit and thedetector pixel included in the detector array.

To determine the association of the optics and detector pixel to thelateral position of incident light at the exterior interface of thesystem (e.g., interface where the system contacts the sample) and thepath length of the optical path, the exemplary system with opticalspacer window can be simplified, as illustrated in FIG. 14C. The angleof light exiting system 1450 at location 1406 can be referred to asexiting angle θ₁, and the angle of scattered light 1451 from location1457 can be referred to as scattering angle θ₂. The scattering angle θ₂can be defined as:

$\begin{matrix}{\theta_{2} = \frac{\theta_{CA1} + {\left( {j - 1} \right)\left( {\theta_{{CA}\; 2} - \theta_{CA1}} \right)}}{j}} & (24)\end{matrix}$

where θ_(CA1) and θ_(CA2) are the range of collection angles and jrepresents the j^(th) detector pixel included in the detector array. Thecorresponding angle of incidence at the spacer-optics unit interface θ₃can be defined as:

$\begin{matrix}{\theta_{3} = {\sin^{- 1}\left( {\frac{n_{sample}}{n_{spacer}}\sin \theta_{2}} \right)}} & (25)\end{matrix}$

where n_(sample) is the refractive index of sample 1420 and n_(spacer)is the refractive index of optical spacer window 1421. The distancebetween location 1447 and the center of optic 1418 can be defined as:

δ(j)=t×tan(θ₃)   (26)

where t is the thickness of optical spacer window 1421. The distance x₁(i.e., lateral position of light) can be defined as:

$\begin{matrix}{{x_{1}\left( {j,m} \right)} = {{\left( {m - 1} \right) \times p} + \frac{p}{2} - {\delta (j)}}} & (27)\end{matrix}$

where m represents the m^(th) optics in the optics unit 1412 and p isthe pitch of optic 1418. The optical path length PL(j,m) of a light raycan be defined as:

$\begin{matrix}{{{PL}\left( {j,m} \right)} = {{d_{11} + d_{12}} = {\left( {\frac{\sin \left( {{90^{\circ}} - \theta_{2}} \right)}{\sin \left( {\theta_{1} + \theta_{2}} \right)} + \frac{\sin \left( {{90^{\circ}} - \theta_{1}} \right)}{\sin \left( {\theta_{1} + \theta_{2}} \right)}} \right){x_{1}\left( {j,m} \right)}}}} & (28)\end{matrix}$

where d₁₁ is the path length of light 1452 and d₁₂ is the path length oflight 1451.

For example, optic 1418 can be configured with a range of collectionangles θ_(CA2) equal to 75° and θ_(CA1) equal to 25°, and opticsincluded in optics unit 1412 can be configured with a pitch of 150 μm.Optical spacer window 1421 can be configured to include sapphire, whichhas a refractive index of 1.74, and can be configured with a thicknessof 500 μm. Optical spacer window 1421 can be in contact with the sample,which can have a refractive index of 1.4 The detector array can beconfigured with 10 detector pixels coupled to the same optics in opticsunit 1412. The exiting angle θ₁ can be 45°, which can lead to scatteringof a light ray with a scattering angle of 45°. The refractive indexdifference between optical spacer window 1421 and sample 1420 can leadthe light ray being incident on the 8^(th) optics in optics unit 1412with angle of incidence θ₃ at the optical spacer window-optics unitinterface to be equal to 34.7° at a distance δ of 346 μm. The lateralposition of the light ray x₁(j,m) can be equal to 779 μm, and theoptical path length of the light ray can be 1.1 mm.

FIGS. 14D-14E illustrate cross-sectional views of an exemplary systemincluding an optical spacer window according to examples of thedisclosure. As illustrated in FIG. 14D, the inclusion of the opticalspacer window in the system can allow a single optics in the optics unitto collect a range of scattering angles. The range of (different)scattering angles can lead to different locations, together forming arange length, on the exterior interface of the system (e.g., interfacewhere the system contacts the sample) that the light rays are incidentupon. In some examples, the thickness of the optical spacer window canbe configured based on the total range length. The optics in the opticsunit can collect light rays from interleaving portions of the sample,and as a result, the aggregate of the optics in the optics unit cancollect multiple angles of incidence and exit location permutationswithout compromising loss of light rays or information.

As illustrated in FIG. 14E, the inclusion of the optical spacer in thesystem can also allow a single location on the exterior interface of thesystem (e.g., interface where the system contacts the sample) to emitlight into multiple optics the optics unit. Although the light rays andinformation can be mixed among multiple optics and multiple detectorpixels, the sum total information can be the same.

One or more of the functions described above can be performed, forexample, by firmware stored in memory and executed by a processor orcontroller. The firmware can also be stored and/or transported withinany non-transitory computer-readable storage medium for use by or inconnection with an instruction execution system, apparatus, or device,such as a computer-based system, processor-containing system, or othersystem that can fetch the instructions from the instruction executionsystem, apparatus, or device and execute the instructions. In thecontext of this document, a “non-transitory computer-readable storagemedium” can be any medium (excluding a signal) that can contain or storethe program for use by or in connection with the instruction executionsystem, apparatus, or device. The non-transitory computer readablestorage medium can include, but is not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, a portable computer diskette (magnetic), a randomaccess memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), anerasable programmable read-only memory (EPROM) (magnetic), a portableoptical disc such as a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flashmemory such as compact flash cards, secured digital cards, USB memorydevices, memory sticks and the like. In the context of this document, a“transport medium” can be any medium that can communicate, propagate, ortransport the program for use by or in connection with the instructionexecution system, apparatus, or device. The transport readable mediumcan include, but is not limited to, an electronic, magnetic, optical,electromagnetic, or infrared wired or wireless propagation medium.

A system for reimaging a plurality of optical paths in a sample isdisclosed. The system can comprise: one or more light sources, eachlight source configured to emit a first light and a second light, thefirst light incident on the sample and including the plurality ofoptical paths, and the second light incident on a reference; a modulatorconfigured to alternate between modulating the first light and thesecond light; one or more optics units configured to collect at least aportion of a reflection of the first light incident on the sample; adetector array including a plurality of detector pixels and configuredto detect at least a portion of the collected reflected first light; andlogic configured to resolve at least one of optical path lengths andangles of incidence of the plurality of optical paths and configured toassociate a detector pixel in the detector array with an optical pathincluded in the plurality of optical paths. Additionally oralternatively, in some examples, the system further comprises: aplurality of units, each unit including: a launch region configured toreflect or absorb one or more wavelengths different from wavelengths oflight emitted from the one or more light sources, a reference regionconfigured to receive a reflection of the second light, and ameasurement region including the one or more optics units, wherein eachunit included the plurality of units is coupled to a measurement regionof the sample. Additionally or alternatively, in some examples, thereference region includes one or more negative lenses configured tospread out the reflection of the second light. Additionally oralternatively, in some examples, each unit is separated from anotherunit by at least 2 mm. Additionally or alternatively, in some examples,at least one unit included in the plurality of units includes at least aportion of the measurement region shared by another unit included in theplurality of units. Additionally or alternatively, in some examples,each unit includes at least one of the one or more light sources, and atleast one unit is configured to measure a region on the sample with adiameter or perimeter less than or equal to 2 mm, the region on thesample including at least 70% of the reflection of the first light.Additionally or alternatively, in some examples, a first surface of atleast one of the one or more optics units is flat and in contact with asurface of the sample, and a second surface of the at least one of theone or more optics unit is convex. Additionally or alternatively, insome examples, the system further comprises a spacer located between theone or more optics units and the sample. Additionally or alternatively,in some examples, the spacer includes sapphire. Additionally oralternatively, in some examples, the spacer has a thickness between400-700 microns. Additionally or alternatively, in some examples, thesystem further comprises an aperture layer located between the spacerand the one or more optics units. Additionally or alternatively, in someexamples, the system further comprises an aperture layer configured toprovide the one or more optics units with access to one or more opticalpaths with a path length in a first range of path lengths and an angleof incidence in a first range of angles, and further configured toreject one or more optical paths with a path length in a second range ofpath lengths, different from the first range of path lengths, having anangle of incidence in a second range of angles, different from the firstrange of angles. Additionally or alternatively, in some examples, theaperture layer is located on a same layer as at least the one or moreoptics units. Additionally or alternatively, in some examples, the oneor more optics units include a plurality of recessed optics.Additionally or alternatively, in some examples, the system furthercomprises a junction located between the one or more light sources andthe sample and further located between the one or more light sources andthe reference, the junction configured to split light emitted from theone or more light sources into the first light and the second light, anintensity of the first light being greater than an intensity of thesecond light. Additionally or alternatively, in some examples, thesystem further comprises: a first outcoupler including a bridge, thefirst outcoupler configured to receive and redirect the first lighttowards the sample; and a second outcoupler including a bridge, thesecond coupler configured to receive and redirect the second lighttowards the reference. Additionally or alternatively, in some examples,the system further comprises one or more optics coupled to the firstoutcoupler and the sample, a first surface of the one or more optics incontact with a surface of the first outcoupler. Additionally oralternatively, in some examples, the system further comprises at leastone of one or more integrated tuning elements, one or more multiplexers,optical routing, one or more waveguides, and integrated circuitryincluded in a silicon-photonics chip. Additionally or alternatively, insome examples, a beam size of at least one of the one or more lightsources is between 100-300 microns. Additionally or alternatively, insome examples, a thickness of at least one of the one or more opticsunits is between 100-300 microns. Additionally or alternatively, in someexamples, the system is included in a package with a size less than 1cm³.

A system is disclosed. The system can comprise: one or more lightsources, each light source configured to emit a first light and a secondlight, the first light directed toward an exterior interface of thesystem and including a plurality of optical paths, and the second lightincident on a reference; one or more first optics configured to collectat least a portion of a reflection of the first light incident on thesample and change an angle of the first light; one or more second opticsconfigured to receive the first light from the one or more first opticsand focus the first light to a detector array; and the detector arrayincluding a plurality of detector pixels and configured to detect atleast a portion of the focused first light from the one or more secondoptics. Additionally or alternatively, in some examples, the systemfurther comprises: a plurality of groups, each group including: a launchregion configured to reflect or absorb one or more wavelengths differentfrom wavelengths of light emitted from the one or more light sources, areference region configured to receive a reflection of the second light,and a measurement region including the one or more first optics.Additionally or alternatively, in some examples, each group includes onelaunch region, one reference region, and a plurality of measurementregions. Additionally or alternatively, in some examples, at least onegroup shares at least a portion of the measurement region with anothergroup. Additionally or alternatively, in some examples, a first surfaceof at least one first optic is flat and located at the exteriorinterface of the system, and a second surface of the at least one opticis convex. Additionally or alternatively, in some examples, the systemfurther comprises: an aperture layer configured to allow one or morefirst optical paths to pass through to the one or more first optics, theone or more second optics, or both, the one or more first optical pathshaving a path length in a first range of path lengths, wherein theaperture layer is further configured to reject one or more secondoptical paths with a path length in a second range of path lengths,different from the first range of path lengths. Additionally oralternatively, in some examples, the system further comprises anaperture layer configured to allow one or more first optical paths topass through to the one or more first optics, the second layer ofoptics, or both, the one or more first optical paths having an angle ofincidence in a first range of angles, wherein the aperture layer isfurther configured to reject one or more second optical paths having anangle of incidence in a second range of angles, different from the firstrange of angles. Additionally or alternatively, in some examples, thesystem further comprises: a junction located between the one or morelight sources and the exterior interface of the system, wherein thejunction is further located between the one or more light sources andthe reference, and wherein the junction is configured to split lightemitted from the one or more light sources into the first light and thesecond light, wherein an intensity of the first light is greater than anintensity of the second light. Additionally or alternatively, in someexamples, the system further comprises: a first outcoupler including abridge, the first outcoupler configured to receive and redirect thefirst light towards the exterior interface of the system; and a secondoutcoupler including a bridge, the second coupler configured to receiveand redirect the second light towards the reference. Additionally oralternatively, in some examples, the system further comprises one ormore third optics coupled to the first outcoupler and the exteriorinterface of the system, wherein a first surface of the one or morethird optics is in contact with a surface of the first outcoupler.Additionally or alternatively, in some examples, the system furthercomprises at least one of one or more integrated tuning elements, one ormore multiplexers, optical routing, one or more waveguides, andintegrated circuitry, wherein the one or more integrated tuning elementsare included in a silicon-photonics chip. Additionally or alternatively,in some examples, each detector pixel is associated with a first opticand a second optic. Additionally or alternatively, in some examples,each first optic is associated with a second optic and a plurality ofthe plurality of detector pixels. Additionally or alternatively, in someexamples, the one or more first optics includes material different frommaterial included in the one or more second optics.

An optical system for determining one or more properties of a sample isdisclosed. In some examples, the optical system comprises: a firstoptics unit disposed on a first substrate and configured for receivingand redirecting a reflection of a first light incident on the sample,the first optics unit including a plurality of first optics, each firstoptics coupled to a detector pixel included in a detector array and anoptical path included in the plurality of optics paths. Additionally oralternatively, in some examples, a surface of the first optics unit isin contact with a surface of the sample and is further configured forfocusing the reflection of the first light towards a surface of thedetector array. Additionally or alternatively, in some examples, theplurality of first optics is configured with a tilt oriented in a samedirection relative to normal incidence. Additionally or alternatively,in some examples, the system further comprises a second optics unitdisposed on a second substrate and configured for receiving and focusingthe first light from the first optics unit, the second optics unitincluding a plurality of second optics, each second optics coupled to afirst optics included in the first optics unit. Additionally oralternatively, in some examples, the first optics unit is attached tothe second optics unit through a plurality of mechanical registrationfeatures formed on the first optics unit, the second optics unit, orboth. Additionally or alternatively, in some examples, each first opticsincludes a prism and is configured to have one or more propertiesdifferent from other first optics. Additionally or alternatively, insome examples, at least one of the first optics includes silicon.Additionally or alternatively, in some examples, each first optics iscoupled to a plurality of detector pixels included in a detector array.Additionally or alternatively, in some examples, at least one of theplurality of first optics is configured with a range of collectionangles equal to 50° and configured with 5-10 angle bins. Additionally oralternatively, in some examples, at least one of the plurality of firstoptics is configured with a range of collection angles centered at 45°.

An optical system is disclosed. The optical system can comprise: one ormore first optics disposed on a first substrate and configured forreceiving and redirecting a first light; one or more second opticsdisposed on a second substrate and configured for receiving the firstlight from the one or more first optics, the one or more second opticsfurther configured to focus the received first light; and an aperturelayer including one or more openings, the aperture layer configured toallow a first portion of incident light to pass through and to prevent asecond portion of the incident light from passing through, wherein theaperture layer is located on a same layer as the one or more firstoptics or the one or more second optics. Additionally or alternatively,in some examples, the aperture layer allows the first portion ofincident light to pass through based on an angle of incidence of theincident light. Additionally or alternatively, in some examples, theaperture layer allows the first portion of incident light to passthrough based on a path length. Additionally or alternatively, in someexamples, the system further comprises: a second aperture layer locatedon a same layer as the one or more second optics, wherein the firstaperture layer is located on a same layer as the one or more firstoptics. Additionally or alternatively, in some examples, the aperturelayer is a lithographic pattern disposed on a surface of the one or morefirst optics or the one or more second optics. Additionally oralternatively, in some examples, the system further comprises: a thirdoptic located on a same layer as the one or more second optics, whereinthe third optic is configured to receive light from a first surface ofthe system and direct light to a second surface of the system, whereinthe one or more first and second optics are configured to receive thefirst light from the second surface of the system.

A method of determining one or more properties of a sample is disclosed.In some examples, the method comprises: determining a first angle ofincidence of a first light at a first interface, the first interfaceincluding the sample and a spacer, the first light emitted from a lightsource; determining a second angle of incidence of a second light at thefirst interface, the second light being a reflection of the first lightand including a first information; determining a third angle ofincidence of a third light at the a second interface, the secondinterface including the spacer and one or more optics units; anddetermining a path length of an optical path based on the first, second,and third angles of incidence. Additionally or alternatively, in someexamples, the system further comprises: determining a fourth angle ofincidence of a fourth light at the first interface, the fourth lightbeing a reflection of the first light originating from a same locationin the sample as the second light originates from and includes a secondinformation, wherein the second light is incident at a first locationalong the first interface and the fourth light is incident at a secondlocation along the second interface, the second location different fromthe first location, further wherein the second and fourth light arecollected by a first optics; and determining a third information basedon an aggregate of the first and second information. Additionally oralternatively, in some examples, the method further comprises:determining a fourth angle of incidence of a fourth light at the firstinterface, the fourth light being a reflection of the first lightoriginating from a same location in the sample as the second lightoriginates from and includes a second information, wherein the secondlight and fourth light are incident at a first location along the firstinterface and incident at a second location along the second interface,further wherein the second light and fourth light are collected bydifferent optics included in the one or more optics units; anddetermining a third information based on an aggregate of the first andsecond information. Additionally or alternatively, in some examples, themethod further comprises: associating the optical path with a opticsincluded in the one or more optics units and a detector pixel includedin a detector array, wherein determining the path length of the opticalpath is further based on a range of collection angles of the optics anda thickness of the spacer. Additionally or alternatively, in someexamples, the optical path is included in a plurality of optical paths,each optical path having a set of information, the set of informationincluding a path length, an angle of incidence, and a location in thesample, wherein each set of information is different from other sets ofinformation included in the plurality of optical paths.

Although the disclosed examples have been fully described with referenceto the accompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the disclosed examples as defined by the appended claims.

1-24. (canceled)
 25. A system for determining properties of a sample,the system comprising: one or more light sources; a detector array; anda first substrate comprising: illumination optics; and first collectionoptics, wherein: the illumination optics and the first collection opticsare formed on one or more surfaces of the first substrate; theillumination optics configured to receive light emitted by the one ormore light sources and redirect the light towards the sample; and thefirst collection optics configured to receive at least a portion of areturn of the light and redirect the light towards the detector array;and the detector array configured to detect the light redirected by thefirst collection optics and generate one or more signals indicative ofthe properties of the sample.
 26. The system of claim 25, furthercomprising: second collection optics configured to receive and redirectat least the portion of the return of the light to the first collectionoptics.
 27. The system of claim 26, wherein the second collection opticsare integrated into a second substrate.
 28. The system of claim 26,wherein the second collection optics are formed on a second substrate.29. The system of claim 28, further comprising: a medium located betweenthe first substrate and the second substrate, wherein the medium has arefractive index such that an angle of the light exiting the secondcollection optics is decreased relative to an angle of the lightincident on the second collection optics.
 30. The system of claim 25,further comprising: a medium located between the first substrate and thedetector array, wherein the medium is a conformal insulating materialthat provides mechanical support.
 31. The system of claim 25, furthercomprising: an aperture layer including one or more openings configuredto selectively allow the light to pass through to the first collectionoptics.
 32. The system of claim 31, wherein: second collection opticsare formed on a second substrate; and the aperture layer is formed onthe one or more surfaces of the second substrate.
 33. The system ofclaim 31, wherein the aperture layer is formed on the one or moresurfaces of the first substrate.
 34. The system of claim 31, wherein theaperture layer is located a focal length away from the first substrate.35. The system of claim 25, further comprising: a second substrateincluding second collection optics, the second collection opticsconfigured to receive the light from the first collection optics andredirect the light to the detector array.
 36. The system of claim 25,wherein the first substrate is located between the sample and thedetector array.
 37. The system of claim 25, wherein the first collectionoptics are integrated into the first substrate.
 38. The system of claim25, further comprising: an outcoupler configured to: receive the lightemitted by the one or more light sources; and redirect the light towardsthe illumination optics, wherein the outcoupler contacts one of the oneor more surfaces of the first substrate.
 39. The system of claim 38,wherein the outcoupler is formed on a third substrate, and the thirdsubstrate is located closer to the first substrate than the detectorarray.
 40. A method for determining properties of a sample, the methodcomprising: receiving light emitted by one or more light sources andredirecting the light towards the sample using illumination optics, theillumination optics formed on one or more surfaces of a first substrate;receiving at least a portion of a return of the light and redirectingthe light towards a detector array using first collection optics, thefirst collection optics formed on the one or more surfaces of the firstsubstrate; detecting the light redirected by the first collection opticsusing the detector array; and generating one or more signals indicativeof at least some properties of the sample using the detector array. 41.The method of claim 40, further comprising: receiving at least theportion of the return of the light and redirecting the light towards thefirst collection optics using second collection optics.
 42. The methodof claim 40, further comprising: decreasing an angle of the lightredirected by the first collection optics.
 43. The method of claim 40,further comprising: selectively allowing the light redirected by thefirst collection optics to pass through using an aperture layer.
 44. Themethod of claim 40, further comprising: receiving the light redirectedby the first collection optics and redirecting the light towards secondcollection optics, the second collection optics formed on one or moresurfaces of a second substrate.